questions.json

{
    "1": {
        "question": "For the input file `addr.txt`, display all lines containing `is`.",
        "ip_file": [
            "addr.txt"
        ],
        "op_file": "This game is good\nToday is sunny\n",
        "ref_solution": [
            "awk '/is/' addr.txt"
        ]
    },
    "2": {
        "question": "For the input file `addr.txt`, display the first field of lines NOT containing `y`. Consider space as the field separator for this file.",
        "ip_file": [
            "addr.txt"
        ],
        "op_file": "Hello\nThis\n12345\n",
        "ref_solution": [
            "awk '!/y/{print $1}' addr.txt"
        ]
    },
    "3": {
        "question": "For the input file `addr.txt`, display all lines containing no more than 2 fields.",
        "ip_file": [
            "addr.txt"
        ],
        "op_file": "Hello World\n12345\n",
        "ref_solution": [
            "awk 'NF<3' addr.txt"
        ]
    },
    "4": {
        "question": "For the input file `patterns.txt`, display all lines containing `is` in the second field. Consider space as the field separator.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "1 dentist 1\n",
        "ref_solution": [
            "awk '$2 ~ /is/' patterns.txt"
        ]
    },
    "5": {
        "question": "For each line of the input file `addr.txt`, replace the first occurrence of `o` with `0`.",
        "ip_file": [
            "addr.txt"
        ],
        "op_file": "Hell0 World\nH0w are you\nThis game is g0od\nT0day is sunny\n12345\nY0u are funny\n",
        "ref_solution": [
            "awk '{sub(/o/, \"0\")} 1' addr.txt"
        ]
    },
    "6": {
        "question": "For the input file `table.txt`, calculate and display the product of numbers in the last field of each line. Consider space as the field separator for this file.",
        "ip_file": [
            "table.txt"
        ],
        "op_file": "-923.16\n",
        "ref_solution": [
            "awk 'BEGIN{p = 1} {p *= $NF} END{print p}' table.txt"
        ]
    },
    "7": {
        "question": "For the input file `addr.txt`, append `.` to all the input lines.",
        "ip_file": [
            "addr.txt"
        ],
        "op_file": "Hello World.\nHow are you.\nThis game is good.\nToday is sunny.\n12345.\nYou are funny.\n",
        "ref_solution": [
            "awk '{print $0 \".\"}' addr.txt",
            "awk '{$0 = $0 \".\"} 1' addr.txt"
        ]
    },
    "8": {
        "question": "For the input file `hex.txt`, replace all occurrences of `0xA0` with `0x50` and `0xFF` with `0x7F`.",
        "ip_file": [
            "hex.txt"
        ],
        "op_file": "start: 0x50, func1: 0x50\nend: 0x7F, func2: 0xB0\nrestart: 0x5010, func3: 0x7F\n",
        "ref_solution": [
            "awk '{gsub(/0xA0/, \"0x50\"); gsub(/0xFF/, \"0x7F\")} 1' hex.txt"
        ]
    },
    "9": {
        "question": "For the input file `patterns.txt`, display all lines that start with `den` or end with `ly`.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "2 lonely\ndent\nlovely\n",
        "ref_solution": [
            "awk '/^den|ly$/' patterns.txt"
        ]
    },
    "10": {
        "question": "For the input file `patterns.txt`, replace all occurrences of `42` with `[42]` unless it is at the edge of a word. Display only the modified lines.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "Hi[42]Bye nice1[42]3 bad42\neqn2 = pressure*3+42/5-1[42]56\ncool_[42]a 42fake\n_[42]_\n",
        "ref_solution": [
            "awk 'gsub(/\\B42\\B/, \"[&]\")' patterns.txt"
        ]
    },
    "11": {
        "question": "For the input file `patterns.txt`, add `[]` around words starting with `s` and containing `e` and `t` in any order. Display only the modified lines.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "[sets] tests Sauerkraut\n[site] cite kite bite [store_2]\n[subtle] sequoia\na [set]\n",
        "ref_solution": [
            "awk 'gsub(/\\<s\\w*(e\\w*t|t\\w*e)\\w*/, \"[&]\")' patterns.txt"
        ]
    },
    "12": {
        "question": "For the input file `patterns.txt`, replace the space character that occurs after a word ending with `a` or `r` with a newline character, only if the line also contains an uppercase letter. Display only the modified lines.\n\nFor example, `A car park` should get converted to `A car` and `park` separated by a newline. But `car far tar` shouldn't be matched as there's no uppercase letter in this line.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "par\ncar\ntar\nfar\nCart\nNot a\npip DOWN\n",
        "ref_solution": [
            "awk '/[A-Z]/ && /[ar]\\> /{print gensub(/([ar])\\> /, \"\\\\1\\n\", \"g\")}' patterns.txt"
        ]
    },
    "13": {
        "question": "For the input file `patterns.txt`, replace all occurrences of `*[5]` with `2`. Display only the modified lines.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "(9-2)2\n",
        "ref_solution": [
            "awk 'gsub(/\\*\\[5]/, \"2\")' patterns.txt"
        ]
    },
    "14": {
        "question": "For the input file `patterns.txt`, display all lines starting with `hand` and ending immediately with `s` or `y` or `le` or no further characters. For example, `handed` shouldn't be matched even though it starts with `hand`.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "handle\nhandy\nhands\nhand\n",
        "ref_solution": [
            "awk '/^hand([sy]|le)?$/' patterns.txt"
        ]
    },
    "15": {
        "question": "For the input file `patterns.txt`, replace `42//5` or `42/5` with `8`. Display only the modified lines.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "eqn3 = r*42-5/3+42///5-83+a\neqn1 = a+8-c\neqn2 = pressure*3+8-14256\n",
        "ref_solution": [
            "awk 'gsub(\"42//?5\", \"8\")' patterns.txt"
        ]
    },
    "16": {
        "question": "For the input file `patterns.txt`, delete from `(` till the next `)`. Display only the modified lines.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "a/b + c%d\n*[5]\ndef factorial\n12- *4)\nHi there. Nice day\n",
        "ref_solution": [
            "awk 'gsub(/\\([^)]*)/, \"\")' patterns.txt"
        ]
    },
    "17": {
        "question": "For the input file `patterns.txt`, delete from `(` till the next `)` but not if there is a `(` character in between. Display only the modified lines.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "a/b + c%d\n*[5]\ndef factorial\n12- (e+*4)\nHi there. Nice day(a\n",
        "ref_solution": [
            "awk 'gsub(/\\([^()]*)/, \"\")' patterns.txt"
        ]
    },
    "18": {
        "question": "For the input file `anchors.txt`, convert markdown anchors to corresponding hyperlinks as shown below.",
        "ip_file": [
            "anchors.txt"
        ],
        "op_file": "[Reg Exp](#reg-exp)\n[Sub calls](#sub-calls)\n[dot meta x](#dot-meta-x)\n",
        "ref_solution": [
            "awk '{print gensub(/<a name=\"([^\"]+)\"><\\/a>(.+)/, \"[\\\\2](#\\\\1)\", 1)}' anchors.txt"
        ]
    },
    "19": {
        "question": "Display lines from `sample.txt` that satisfy both of these conditions:\n\n\u2022 `to` or `he` matched irrespective of case\n\u2022 `World` or `No` matched case sensitively",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "Hello World\nNo doubt you like it too\n",
        "ref_solution": [
            "awk 'tolower($0) ~ /to|he/ && /World|No/' sample.txt"
        ]
    },
    "20": {
        "question": "The input file `f2.txt` has fields separated by `,` and field values cannot be empty. Replace the third field with `42`.",
        "ip_file": [
            "f2.txt"
        ],
        "op_file": "lion,ant,42,neon\n_;3%,.,42,:\n\"apple\",banana,42,guava\n",
        "ref_solution": [
            "awk '{print gensub(/[^,]+/, \"42\", 3)}' f2.txt",
            "awk -F, -v OFS=, '{$3 = 42} 1' f2.txt"
        ]
    },
    "21": {
        "question": "For the input file `patterns.txt`, filter lines containing three or more occurrences of `ar`. For such lines, replace the third from last occurrence of `ar` with `X`.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "par car tX far Cart\npXt cart mart\n",
        "ref_solution": [
            "awk 'BEGIN{r = @/(.*)ar((.*ar){2})/} $0~r{print gensub(r, \"\\\\1X\\\\2\", 1)}' patterns.txt",
            "awk -F'ar' 'NF>3{print gensub(FS, \"X\", NF-3)}' patterns.txt"
        ]
    },
    "22": {
        "question": "For the input file `f1.txt`, surround all whole words with `()`. Additionally, if the whole word is `imp` or `ant`, delete them.",
        "ip_file": [
            "f1.txt"
        ],
        "op_file": "(tiger) () (goat)\n(eagle) () (important)\n(Apple):(FIG):(banana2)\n()-(imp_42)-()-()-(_ant)\n",
        "ref_solution": [
            "awk '{print gensub(/\\<(imp|ant|(\\w+))\\>/, \"(\\\\2)\", \"g\")}' f1.txt"
        ]
    },
    "23": {
        "question": "For the input file `patterns.txt`, display lines containing `car` but not as a whole word. For example, `scared-cat` and `car care` should match but not `far car park`.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "scar\ncare\na huge discarded pile of books\nscare\npart cart mart\n",
        "ref_solution": [
            "awk '/\\Bcar|car\\B/' patterns.txt"
        ]
    },
    "24": {
        "question": "For the input file `patterns.txt`, display lines starting with `4` or `-` or `u` or `sub` or `care`.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "care\n4*5]\n-handy\nsubtle sequoia\nunhand\n",
        "ref_solution": [
            "awk '/^([4u-]|sub|care)/' patterns.txt"
        ]
    },
    "25": {
        "question": "For the input file `f3.txt`, replace sequences made up of words separated by `:` or `.` by the first word of the sequence. Such sequences will end when `:` or `.` is not followed by a word character.",
        "ip_file": [
            "f3.txt"
        ],
        "op_file": "wow hi-2 bye\nkite apple\n",
        "ref_solution": [
            "awk '{gsub(/([:.]\\w*)+/, \"\")} 1' f3.txt"
        ]
    },
    "26": {
        "question": "For the input file `f3.txt`, replace sequences made up of words separated by `:` or `.` by the last word of the sequence. Such sequences will end when `:` or `.` is not followed by a word character.",
        "ip_file": [
            "f3.txt"
        ],
        "op_file": "five hi-2 bye\nwater fig\n",
        "ref_solution": [
            "awk '{print gensub(/((\\w+)[:.])+/, \"\\\\2\", \"g\")}' f3.txt"
        ]
    },
    "27": {
        "question": "For the input file `f4.txt`, replace all whole words with `X` unless it is preceded by a `(` character.",
        "ip_file": [
            "f4.txt"
        ],
        "op_file": "X (apple) X) X\n(mango) (grape\n",
        "ref_solution": [
            "awk '{print gensub(/(^|[^(])\\<\\w+/, \"\\\\1X\", \"g\")}' f4.txt"
        ]
    },
    "28": {
        "question": "For the input file `f5.txt`, surround whole words with `[]` only if they are followed by `:` or `,` or `-`.",
        "ip_file": [
            "f5.txt"
        ],
        "op_file": "[Poke],on=-=[so_good]:ink\nto/is(vast)[ever2]-sit\n[apple],[banana]:[fig]-grape\n",
        "ref_solution": [
            "awk '{print gensub(/(\\w+)([:,-])/, \"[\\\\1]\\\\2\", \"g\")}' f5.txt"
        ]
    },
    "29": {
        "question": "The `fields.txt` file has fields separated by the `:` character. Delete `:` and the last field if there is a digit character anywhere before the last field.",
        "ip_file": [
            "fields.txt"
        ],
        "op_file": "42\ntwelve:a2b\nwe:be:he:0:a:b\napple:banana-42:cherry\ndragon:unicorn:centaur\n",
        "ref_solution": [
            "awk '{print gensub(/([0-9].*):.*/, \"\\\\1\", 1)}' fields.txt",
            "awk '/[0-9].*:/{sub(/:[^:]*$/, \"\")} 1' fields.txt"
        ]
    },
    "30": {
        "question": "For the input file `patterns.txt`, surround all hexadecimal sequences with a minimum of four characters with `[]`. Match `0x` as an optional prefix, but shouldn't be counted for determining the length. Match the characters case insensitively, and the sequences shouldn't be surrounded by other word characters. Display only the modified lines.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "\"should not match [0XdeadBEEF]\"\nHi42Bye nice1423 [bad42]\ntook 0xbad 22 [0x0ff1ce]\neqn2 = pressure*3+42/5-[14256]\n",
        "ref_solution": [
            "awk -v IGNORECASE=1 'gsub(/\\<(0x)?[0-9a-f]{4,}\\>/, \"[&]\")' patterns.txt",
            "awk 'gsub(/\\<(0[xX])?[[:xdigit:]]{4,}\\>/, \"[&]\")' patterns.txt"
        ]
    },
    "31": {
        "question": "For the input file `brackets.txt`, extract only the contents between `()` or `)(` from each input line. Assume that `()` characters will be present only once every line.",
        "ip_file": [
            "brackets.txt"
        ],
        "op_file": "ice\nalmond-pista\nyoyo\n",
        "ref_solution": [
            "awk -F'[()]' '{print $2}' brackets.txt"
        ]
    },
    "32": {
        "question": "For the input file `scores.csv`, extract `Name` and `Physics` fields in the format shown below.",
        "ip_file": [
            "scores.csv"
        ],
        "op_file": "Name:Physics\nBlue:46\nLin:83\nEr:79\nCy:98\nOrt:72\nIth:100\n",
        "ref_solution": [
            "awk -F, -v OFS=: '{print $1, $3}' scores.csv",
            "awk -F, '{print $1 \":\" $3}' scores.csv"
        ]
    },
    "33": {
        "question": "For the input file `scores.csv`, display names of those who've scored above `70` in Maths.",
        "ip_file": [
            "scores.csv"
        ],
        "op_file": "Lin\nCy\nIth\n",
        "ref_solution": [
            "awk -F, '+$2>70{print $1}' scores.csv"
        ]
    },
    "34": {
        "question": "Display the number of word characters for each line of `f6.txt`. Word definition here is same as used in regular expressions.",
        "ip_file": [
            "f6.txt"
        ],
        "op_file": "7\n0\n12\n0\n",
        "ref_solution": [
            "awk -F'\\\\w' '{print NF ? NF-1 : 0}' f6.txt",
            "awk '{print gsub(/\\w/, \"\")}' f6.txt"
        ]
    },
    "35": {
        "question": "For the input file `quoted.txt`, extract the first and third sequence of characters surrounded by double quotes and display them in the format shown below. Solution shouldn't use substitution functions.",
        "ip_file": [
            "quoted.txt"
        ],
        "op_file": "\"grape\",\"guava\"\n\"a 1\",\"c-2\"\n",
        "ref_solution": [
            "awk -v FPAT='\"[^\"]+\"' -v OFS=, '{print $1, $3}' quoted.txt"
        ]
    },
    "36": {
        "question": "For the input file `varying_fields.txt`, construct a solution to get the output shown below. Solution shouldn't use substitution functions.",
        "ip_file": [
            "varying_fields.txt"
        ],
        "op_file": "hi,bye,to\n1,2,5\n",
        "ref_solution": [
            "awk -F, -v OFS=, '{$3=$NF; NF=3} 1' varying_fields.txt"
        ]
    },
    "37": {
        "question": "Transform the given input file `fw.txt` to get the output as shown below. If a field is empty (i.e. contains only space characters), replace it with `NA`.",
        "ip_file": [
            "fw.txt"
        ],
        "op_file": "1.3,rs,0.134563\n3.8,NA,6\n5.2,ye,8.2387\n4.2,kt,45.1\n",
        "ref_solution": [
            "awk -v FIELDWIDTHS='3 2:2 3:2 2:*' -v OFS=, '$2==\"  \"{$2=\"NA\"} {print $1, $2, $4}' fw.txt"
        ]
    },
    "38": {
        "question": "Display only the third and eighth characters from each line of `table.txt`.",
        "ip_file": [
            "table.txt"
        ],
        "op_file": "or\nuk\nlb\n",
        "ref_solution": [
            "awk -F '' -v OFS= '{print $3, $8}' table.txt",
            "awk '{print substr($0, 3, 1) substr($0, 8, 1)}' table.txt"
        ]
    },
    "39": {
        "question": "The `fields.txt` file has fields separated by the `:` character. Delete `:` and the last field if there is a digit character anywhere before the last field. Solution shouldn't use substitution functions.",
        "ip_file": [
            "fields.txt"
        ],
        "op_file": "42\ntwelve:a2b\nwe:be:he:0:a:b\napple:banana-42:cherry\ndragon:unicorn:centaur\n",
        "ref_solution": [
            "awk -F: -v OFS=: '/[0-9].*:/{NF--} 1' fields.txt"
        ]
    },
    "40": {
        "question": "For the input file `f7.txt`, retain up to the first three fields. `^` is the input field separator. Use `,` as the output field separator.",
        "ip_file": [
            "f7.txt"
        ],
        "op_file": "sit,eat,very\napple:42,fig:100\n1,,3\n",
        "ref_solution": [
            "awk -F'^' -v OFS=, '{NF = NF>2 ? 3 : NF} 1' f7.txt"
        ]
    },
    "41": {
        "question": "The `f8.txt` file uses `cat` as the field separator (irrespective of case). Use space as the output field separator and add `42` as the last field.",
        "ip_file": [
            "f8.txt"
        ],
        "op_file": "apple fig 12345 banana 42\n  42\n(dragon) (unicorn) 42\n",
        "ref_solution": [
            "awk -F'cat' -v IGNORECASE=1 '{$(NF+1)=42} 1' f8.txt"
        ]
    },
    "42": {
        "question": "For the input file `sample.txt`, filter lines containing 6 or more lowercase vowels.",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "No doubt you like it too\nMuch ado about nothing\n",
        "ref_solution": [
            "awk -F'[aeiou]' 'NF>6' sample.txt"
        ]
    },
    "43": {
        "question": "The input file `concat.txt` has contents of various files preceded by a line starting with `###`. Replace such sequence of characters with an incrementing integer value (starting with `1`) in the format shown below.",
        "ip_file": [
            "concat.txt"
        ],
        "op_file": "1) addr.txt\nHow are you\nThis game is good\nToday is sunny\n2) broken.txt\ntop\n1234567890\nbottom\n3) sample.txt\nJust do-it\nBelieve it\n4) mixed_fs.txt\npink blue white yellow\ncar,mat,ball,basket\n",
        "ref_solution": [
            "awk '$1==\"###\"{$1 = ++c \")\"} 1' concat.txt"
        ]
    },
    "44": {
        "question": "The input file `jumbled.txt` consists of words separated by various delimiters. Display all words that contain `an` or `at` or `in` or `it`, one per line.",
        "ip_file": [
            "jumbled.txt"
        ],
        "op_file": "overcoats\nfurrowing\nwavering\njoint\nintuition\ntitanic\n",
        "ref_solution": [
            "awk -v RS='\\\\W+' '/[ai][nt]/' jumbled.txt"
        ]
    },
    "45": {
        "question": "For the input file `f9.txt`, join all input lines with the `,` character. Make sure that there's no `,` at end of the line and that there's a newline character at the end of the line. In other words, emulate `paste -sd,` with `awk`.",
        "ip_file": [
            "f9.txt"
        ],
        "op_file": "apple fig,42,100,a b c\n",
        "ref_solution": [
            "awk -v ORS= 'NR>1{print \",\"} 1; END{print \"\\n\"}' f9.txt"
        ]
    },
    "46": {
        "question": "For the input file `scores.csv`, add another column named GP which is calculated out of 100 by giving 50% weightage to Maths and 25% each for Physics and Chemistry.",
        "ip_file": [
            "scores.csv"
        ],
        "op_file": "Name,Maths,Physics,Chemistry,GP\nBlue,67,46,99,69.75\nLin,78,83,80,79.75\nEr,56,79,92,70.75\nCy,97,98,95,96.75\nOrt,68,72,66,68.5\nIth,100,100,100,100\n",
        "ref_solution": [
            "awk -F, -v OFS=, '{$(NF+1) = NR==1 ? \"GP\" : ($2/2 + ($3+$4)/4)} 1' scores.csv"
        ]
    },
    "47": {
        "question": "For the input file `sample.txt`, extract all paragraphs containing `do` and exactly two lines.",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "Just do-it\nBelieve it\n\nMuch ado about nothing\nHe he he\n",
        "ref_solution": [
            "awk -F'\\n' -v RS= 'NF==2 && /do/{print s $0; s=\"\\n\"}' sample.txt"
        ]
    },
    "48": {
        "question": "For the input file `ip.txt`, change each paragraph to a single line by joining lines using `.` and a space character as the separator. Also, add a final `.` to each paragraph.",
        "ip_file": [
            "ip.txt"
        ],
        "op_file": "hello.\n\nworld.\n\napple. banana. cherry.\n\ntea coffee. chocolate.\n",
        "ref_solution": [
            "awk 'BEGIN{FS=\"\\n\"; OFS=\". \"; RS=\"\"} {$NF=$NF \".\"; print s $0; s=\"\\n\"}' ip.txt"
        ]
    },
    "49": {
        "question": "The various input/output separators can be changed dynamically and comes into effect during the next input/output operation. For the input file `mixed_fs.txt`, retain only the first two fields from each input line. The field separators should be space for the first two lines and `,` for the rest of the lines.",
        "ip_file": [
            "mixed_fs.txt"
        ],
        "op_file": "rose lily\npink blue\ncar,mat\ngreen,brown\n",
        "ref_solution": [
            "awk 'NF=2; NR==2{FS=OFS=\",\"}' mixed_fs.txt"
        ]
    },
    "50": {
        "question": "For the input file `table.txt`, print other than the second line.",
        "ip_file": [
            "table.txt"
        ],
        "op_file": "brown bread mat hair 42\nyellow banana window shoes 3.14\n",
        "ref_solution": [
            "awk 'NR!=2' table.txt"
        ]
    },
    "51": {
        "question": "For the input file `table.txt`, print only the line number for lines containing `air` or `win`.",
        "ip_file": [
            "table.txt"
        ],
        "op_file": "1\n3\n",
        "ref_solution": [
            "awk '/air|win/{print NR}' table.txt"
        ]
    },
    "52": {
        "question": "For the input file `table.txt`, calculate the sum of numbers in the last column, excluding the second line.",
        "ip_file": [
            "table.txt"
        ],
        "op_file": "45.14\n",
        "ref_solution": [
            "awk 'NR!=2{sum += $NF} END{print sum}' table.txt"
        ]
    },
    "53": {
        "question": "For the input file `sample.txt`, print the second and fourth line for every block of five lines.",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "\nHow are you\nBelieve it\nToday is sunny\n\nHe he he\n",
        "ref_solution": [
            "awk 'NR%5 == 2 || NR%5 == 4' sample.txt",
            "awk 'BEGIN{a[2]; a[4]} (NR%5) in a' sample.txt"
        ]
    },
    "54": {
        "question": "For the input file `odd.txt`, surround all whole words with `{}` that start and end with the same word character. This is a contrived exercise to make you use the `RT` variable (`sed -E 's/\\b(\\w)(\\w*\\1)?\\b/{&}/g' odd.txt` would be a simpler solution).",
        "ip_file": [
            "odd.txt"
        ],
        "op_file": "-{oreo}-not:{a} {_a2_} {roar}\n{RoaR} to {wow}-\n",
        "ref_solution": [
            "awk -F '' -v RS='\\\\W+' -v ORS= '$0 && $1==$NF{$0 = \"{\" $0 \"}\"} {print $0 RT}' odd.txt"
        ]
    },
    "55": {
        "question": "Print only the second field of the third line, if any, from these input files: `addr.txt`, `sample.txt` and `copyright.txt`. Consider space as the field separator.",
        "ip_file": [
            "addr.txt",
            "sample.txt",
            "copyright.txt"
        ],
        "op_file": "game\nday\nbla\n",
        "ref_solution": [
            "awk 'FNR==3{print $2}' addr.txt sample.txt copyright.txt"
        ]
    },
    "56": {
        "question": "The input file `ip.txt` has varying amount of empty lines between the records, change them to be always two empty lines. Also, remove the empty lines at the start and end of the file.",
        "ip_file": [
            "ip.txt"
        ],
        "op_file": "hello\n\n\nworld\n\n\napple\nbanana\ncherry\n\n\ntea coffee\nchocolate\n",
        "ref_solution": [
            "awk -v RS= '{print s $0; s=\"\\n\\n\"}' ip.txt"
        ]
    },
    "57": {
        "question": "The `f10.txt` file uses `cat` as the record separator (irrespective of case). Display only the even numbered records separated by a single empty line.",
        "ip_file": [
            "f10.txt"
        ],
        "op_file": "fig\n\n\nbanana\n\n:mango\n",
        "ref_solution": [
            "awk -v RS='cat' -v IGNORECASE=1 'NR%2==0{print s $0; s=\"\\n\"}' f10.txt"
        ]
    },
    "58": {
        "question": "The input file `nums.txt` contains a single column of numbers. If the number starts with a `-` sign, remove it and vice versa. Solution should use the `sub` function and shouldn't explicitly use the `if-else` control structure or the ternary operator.",
        "ip_file": [
            "nums.txt"
        ],
        "op_file": "-42\n2\n-10101\n3.14\n75\n-2.3e4\n-0\n",
        "ref_solution": [
            "awk '!sub(/^-/, \"\"){sub(/^/, \"-\")} 1' nums.txt"
        ]
    },
    "59": {
        "question": "For the input file `table.txt`, change the field separator from space to the `,` character. Retain only the first three fields and any field containing `b` or `g` should be surrounded by double quotes.",
        "ip_file": [
            "table.txt"
        ],
        "op_file": "\"brown\",\"bread\",mat\n\"blue\",cake,\"mug\"\nyellow,\"banana\",window\n",
        "ref_solution": [
            "awk -v q='\"' -v OFS=, '{NF=3; for(i=1; i<=NF; i++) if($i ~ /[bg]/) $i = q $i q} 1' table.txt"
        ]
    },
    "60": {
        "question": "For each input line of the file `secrets.txt`, remove all characters except the last character of each field. Assume space as the input field separator.",
        "ip_file": [
            "secrets.txt"
        ],
        "op_file": "gawk\nfield\nice-2\n",
        "ref_solution": [
            "awk -v OFS= '{for(i=1; i<=NF; i++) $i = gensub(/.*(.)/, \"\\\\1\", 1, $i)} 1' secrets.txt",
            "awk '{print gensub(/[^ ]*(.)( |$)/, \"\\\\1\", \"g\")}' secrets.txt",
            "awk -v OFS= '{for(i=1; i<=NF; i++) $i = substr($i, length($i))} 1' secrets.txt"
        ]
    },
    "61": {
        "question": "For the input file `sample.txt`, display from the start of the file till a line containing `are`. In other words, emulate the `q` command of `sed`.",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "Hello World\n\nGood day\nHow are you\n",
        "ref_solution": [
            "awk '1; /are/{exit}' sample.txt"
        ]
    },
    "62": {
        "question": "For the input file `sample.txt`, display from the start of the file till a line containing `are`, but exclude the matching line. In other words, emulate the `Q` command of `sed`.",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "Hello World\n\nGood day\n",
        "ref_solution": [
            "awk '/are/{exit} 1' sample.txt"
        ]
    },
    "63": {
        "question": "For the input file `scores.csv`, sort the rows in descending order based on the values in the Physics column. Header should be retained as the first line in the output.",
        "ip_file": [
            "scores.csv"
        ],
        "op_file": "Name,Maths,Physics,Chemistry\nIth,100,100,100\nCy,97,98,95\nLin,78,83,80\nEr,56,79,92\nOrt,68,72,66\nBlue,67,46,99\n",
        "ref_solution": [
            "awk -F, 'NR==1{PROCINFO[\"sorted_in\"] = \"@ind_num_desc\"; print; next} {a[$3]=$0} END{for(k in a) print a[k]}' scores.csv"
        ]
    },
    "64": {
        "question": "For the input file `nums1.txt`, display the square root of numbers in the scientific notation, with four digits after the fractional point. Assume that the input has only a single column of positive numbers.",
        "ip_file": [
            "nums1.txt"
        ],
        "op_file": "1.7720e+00\n6.4815e+01\n2.7875e+01\n5.6834e+02\n",
        "ref_solution": [
            "awk '{printf \"%.4e\\n\", sqrt($0)}' nums1.txt",
            "awk '{printf \"%.4e\\n\", $0**0.5}' nums1.txt"
        ]
    },
    "65": {
        "question": "For the input file `items.txt`, assume space as the field separator. From the second field, remove the second `:` character and the number that follows. Modify the last field by multiplying it by the number that was deleted from the second field.",
        "ip_file": [
            "items.txt"
        ],
        "op_file": "apple rxg:12 og -2635\nfig zwt:3.64 ljg 6445\nbanana ysl:42 vle 141.3\n",
        "ref_solution": [
            "awk '{split($2, a, /:/); $2=a[1] \":\" a[2]; $NF *= a[3]} 1' items.txt"
        ]
    },
    "66": {
        "question": "For the input file `sum.txt`, assume space as the field separator. Replace the second field with the sum of the two numbers embedded in it. The numbers can be positive/negative integers or floating-point numbers but not scientific notation.",
        "ip_file": [
            "sum.txt"
        ],
        "op_file": "f2:z3 -38.86 5y6\nt5:x7 -8754.12 u9\napple:fig 132 9j4\n",
        "ref_solution": [
            "awk '{patsplit($2, a, /-?[0-9]+(\\.[0-9]+)?/); $2=a[1] + a[2]} 1' sum.txt"
        ]
    },
    "67": {
        "question": "For the input file `f11.txt`, extract all positive integers preceded by `-` and followed by `:` or `;`. Display the matching portions separated by a newline character.",
        "ip_file": [
            "f11.txt"
        ],
        "op_file": "5\n20\n34\n",
        "ref_solution": [
            "awk '{ while(match($0, /-([0-9]+)[;:]/, m)){print m[1]; $0=substr($0, RSTART+RLENGTH)} }' f11.txt",
            "awk -v RS='-[0-9]+[;:]' 'RT{print substr(RT, 2, length(RT)-2)}' f11.txt"
        ]
    },
    "68": {
        "question": "For the input file `files.txt`, replace lines starting with a space with the output of that line executed as a shell command.",
        "ip_file": [
            "files.txt"
        ],
        "op_file": "How are you\n-----------\n31 sample.txt\n===========\nbrown\nblue\nyellow\n-----------\n",
        "ref_solution": [
            "awk '/^ /{system($0); next} 1' files.txt"
        ]
    },
    "69": {
        "question": "For the input file `fw.txt`, format the last column in scientific notation with two digits after the decimal point.",
        "ip_file": [
            "fw.txt"
        ],
        "op_file": "1.3  rs   90  1.35e-01\n3.8           6.00e+00\n5.2  ye       8.24e+00\n4.2  kt   32  4.51e+01\n",
        "ref_solution": [
            "awk -v FIELDWIDTHS='14 *' '{printf \"%s%.2e\\n\", $1, $2}' fw.txt"
        ]
    },
    "70": {
        "question": "For the input file `addr.txt`, display all lines containing `e` or `u` but not both.",
        "ip_file": [
            "addr.txt"
        ],
        "op_file": "Hello World\nThis game is good\nToday is sunny\n",
        "ref_solution": [
            "awk 'xor(/e/, /u/)' addr.txt",
            "awk '(/e/ && !/u/) || (!/e/ && /u/)' addr.txt"
        ]
    },
    "71": {
        "question": "For the input file `patterns.txt`, filter lines containing `[5]` at the start of a line. The search term should be matched literally.",
        "ip_file": [
            "patterns.txt"
        ],
        "op_file": "[5]*3\n",
        "ref_solution": [
            "awk 'index($0, \"[5]\")==1' patterns.txt"
        ]
    },
    "72": {
        "question": "For the input file `table.txt`, uppercase the third field.",
        "ip_file": [
            "table.txt"
        ],
        "op_file": "brown bread MAT hair 42\nblue cake MUG shirt -7\nyellow banana WINDOW shoes 3.14\n",
        "ref_solution": [
            "awk '{$3 = toupper($3)} 1' table.txt"
        ]
    },
    "73": {
        "question": "Print the last field of the first two lines for the input files `table.txt`, `scores.csv` and `fw.txt`. The field separators for these files are space, comma and fixed width respectively. To make the output more informative, print filenames and a separator as shown in the output below. Assume that the input files will have at least two lines.",
        "ip_file": [
            "table.txt",
            "scores.csv",
            "fw.txt"
        ],
        "op_file": ">table.txt<\n42\n-7\n----------\n>scores.csv<\nChemistry\n99\n----------\n>fw.txt<\n0.134563\n6\n----------\n",
        "ref_solution": [
            "awk 'BEGINFILE{print \">\" FILENAME \"<\"} {print $NF} FNR==2{print \"----------\"; nextfile}' table.txt FS=, scores.csv FIELDWIDTHS='14 *' fw.txt"
        ]
    },
    "74": {
        "question": "For the input files `sample.txt`, `secrets.txt`, `addr.txt` and `table.txt`, display only the names of files that contain `in` or `at` or `fun` in the third field. Assume space as the field separator. The output should not show a matching filename more than once.",
        "ip_file": [
            "sample.txt",
            "secrets.txt",
            "addr.txt",
            "table.txt"
        ],
        "op_file": "secrets.txt\naddr.txt\ntable.txt\n",
        "ref_solution": [
            "awk '$3 ~ /fun|at|in/{print FILENAME; nextfile}' sample.txt secrets.txt addr.txt table.txt"
        ]
    },
    "75": {
        "question": "For the input file `sample.txt`, print lines containing `do` only if the previous line is empty and the line before that contains `you`.",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "Just do-it\nMuch ado about nothing\n",
        "ref_solution": [
            "awk 'p2 ~ /you/ && p1==\"\" && /do/; {p2=p1; p1=$0}' sample.txt"
        ]
    },
    "76": {
        "question": "For the input file `sample.txt`, match lines containing `do` or `not` case insensitively. Each of these terms occur multiple times in the file. The goal is to print only the second occurrences of these terms (independent of each other).",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "No doubt you like it too\nMuch ado about nothing\n",
        "ref_solution": [
            "awk -v IGNORECASE=1 '/do/ && ++d == 2; /not/ && ++n == 2' sample.txt"
        ]
    },
    "77": {
        "question": "For the input file `sample.txt`, print the matching lines containing `are` or `bit` as well as `n` lines around the matching lines. The value for `n` is passed to the `awk` command via the `-v` option. Use `n=2` for this exercise.",
        "ip_file": [
            "sample.txt"
        ],
        "op_file": "\nGood day\nHow are you\n\nJust do-it\n\nToday is sunny\nNot a bit funny\nNo doubt you like it too\n\n",
        "ref_solution": [
            "awk -v n=2 '/are|bit/{for(i=NR-n; i<NR; i++) if(i>0) print a[i]; c=n+1} c && c--; {a[NR]=$0}' sample.txt"
        ]
    },
    "78": {
        "question": "The input file `broken.txt` starts with a line containing `top` followed by some content before a line containing `bottom` is found. Blocks of lines bounded by these two markers repeats except for the last block as it is missing the `bottom` marker. Print all lines between the markers `top` and `bottom`.",
        "ip_file": [
            "broken.txt"
        ],
        "op_file": "3.14\n1234567890\n",
        "ref_solution": [
            "tac broken.txt | awk '/top/{f=0} f; /bottom/{f=1}' | tac"
        ]
    },
    "79": {
        "question": "For the input file `concat.txt`, extract contents from a line starting with ``### `` until but not including the next such line. The block to be extracted is indicated by the variable `n` passed via the `-v` option. Use `n=4` for this exercise.",
        "ip_file": [
            "concat.txt"
        ],
        "op_file": "### mixed_fs.txt\npink blue white yellow\ncar,mat,ball,basket\n",
        "ref_solution": [
            "awk -v n=4 '/^### /{c++} c==n' concat.txt"
        ]
    },
    "80": {
        "question": "For the input file `lines.txt`, delete the line that comes after a whole line containing `---`. Assume that such lines won't occur consecutively.",
        "ip_file": [
            "lines.txt"
        ],
        "op_file": "Go There\ncome on\ngo there\n---\ncome on!\n---\nCOME ON\n",
        "ref_solution": [
            "awk 'p!=\"---\"; {p=$0}' lines.txt",
            "awk '!(n && n--); $0==\"---\"{n=1}' lines.txt"
        ]
    },
    "81": {
        "question": "For the input file `result.csv`, use `---` to separate entries with the same name in the first column. Assume that the lines with the same first column value will always be next to each other.",
        "ip_file": [
            "result.csv"
        ],
        "op_file": "Amy,maths,89\nAmy,physics,75\n---\nJoe,maths,79\n---\nJohn,chemistry,77\nJohn,physics,91\n---\nMoe,maths,81\n---\nRavi,physics,84\nRavi,chemistry,70\n---\nYui,maths,92\n",
        "ref_solution": [
            "awk -F, 'NR>1 && p!=$1{print \"---\"} 1; {p=$1}' result.csv"
        ]
    },
    "82": {
        "question": "Use the contents of `match_words.txt` file to display matching lines from `jumbled.txt` and `sample.txt`. The matching criteria is that the second word of lines from these files should match the third word of lines from `match_words.txt`.",
        "ip_file": [
            "match_words.txt",
            "jumbled.txt",
            "sample.txt"
        ],
        "op_file": "wavering:concession/woof\\retailer\nNo doubt you like it too\n",
        "ref_solution": [
            "awk -v FPAT='\\\\w+' 'NR==FNR{a[$3]; next} $2 in a' match_words.txt jumbled.txt sample.txt"
        ]
    },
    "83": {
        "question": "Interleave the contents of `secrets.txt` with the contents of a file indicated by the variable `f` passed via the `-v` option as shown below. Use `f='table.txt'` for this exercise.",
        "ip_file": [
            "secrets.txt",
            "table.txt"
        ],
        "op_file": "stag area row tick\nbrown bread mat hair 42\n---\ndeaf chi rate tall glad\nblue cake mug shirt -7\n---\nBi tac toe - 42\nyellow banana window shoes 3.14\n---\n",
        "ref_solution": [
            "awk -v f='table.txt' '{print; getline < f; print; print \"---\"}' secrets.txt"
        ]
    },
    "84": {
        "question": "Display lines from `scores.csv` by matching the first field based on a list of names from the `names.txt` file. Also, change the output field separator to a space character.",
        "ip_file": [
            "names.txt",
            "scores.csv"
        ],
        "op_file": "Lin 78 83 80\nCy 97 98 95\nIth 100 100 100\n",
        "ref_solution": [
            "awk -F, 'NR==FNR{a[$1]; next} $1 in a{$1=$1; print}' names.txt scores.csv"
        ]
    },
    "85": {
        "question": "The `result.csv` file has three columns \u2014 name, subject and mark. The `criteria.txt` file has two columns \u2014 name and subject. Match lines from `result.csv` based on the two columns from `criteria.txt` provided the mark column is greater than 80.",
        "ip_file": [
            "result.csv",
            "criteria.txt"
        ],
        "op_file": "Amy,maths,89\nJohn,physics,91\nYui,maths,92\n",
        "ref_solution": [
            "awk 'NR==FNR{a[$1,$2]; next} ($1,$2) in a && $3 > 80' criteria.txt FS=, result.csv"
        ]
    },
    "86": {
        "question": "Retain only the first copy of a line for the input file `lines.txt`. Case should be ignored while comparing the lines. For example, `hi there` and `HI TheRE` should be considered as duplicates.",
        "ip_file": [
            "lines.txt"
        ],
        "op_file": "Go There\ncome on\n---\n2 apples and 5 mangoes\ncome on!\n2 Apples\n",
        "ref_solution": [
            "awk '!seen[tolower($0)]++' lines.txt"
        ]
    },
    "87": {
        "question": "Retain only the first copy of a line for the input file `twos.txt`. Assume space as the field separator with exactly two fields per line. Compare the lines irrespective of the order of the fields. For example, `hehe haha` and `haha hehe` should be considered as duplicates.",
        "ip_file": [
            "twos.txt"
        ],
        "op_file": "hehe haha\ndoor floor\n6;8 3-4\ntrue blue\nhehe bebe\ntru eblue\n",
        "ref_solution": [
            "awk '!($1,$2) in seen && !($2,$1) in seen; {seen[$1,$2]}' twos.txt"
        ]
    },
    "88": {
        "question": "For the input file `twos.txt`, display only the unique lines. Assume space as the field separator with exactly two fields per line. Compare the lines irrespective of the order of the fields. For example, `hehe haha` and `haha hehe` should be considered as duplicates.",
        "ip_file": [
            "twos.txt"
        ],
        "op_file": "true blue\nhehe bebe\ntru eblue\n",
        "ref_solution": [
            "awk 'NR==FNR{c[$1,$2]++; next} c[$1,$2] + c[$2,$1] == 1' twos.txt twos.txt"
        ]
    }
}