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141 lines
4.2 KiB
Plaintext
141 lines
4.2 KiB
Plaintext
# awk
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# Pattern scanning and processing language
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# Sum integers from a file or STDIN, one integer per line.
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printf '1\n2\n3\n' | awk '{sum += $1} END {print sum}'
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# Using specific character as separator to sum integers from a file or STDIN.
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printf '1:2:3' | awk -F ":" '{print $1+$2+$3}'
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# Print line number 12 of file.txt
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awk 'NR==12' file.txt
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# Print first field for each record in file.txt
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awk '{print $1}' file.txt
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Print only lines that match regex in file.txt
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awk '/regex/' file.txt
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# Print only lines that do not match regex in file.txt
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awk '!/regex/' file.txt
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# Print any line where field 2 is equal to "foo" in file.txt
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awk '$2 == "foo"' file.txt
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# Print lines where field 2 is NOT equal to "foo" in file.txt
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awk '$2 != "foo"' file.txt
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# Print line if field 1 matches regex in file.txt
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awk '$1 ~ /regex/' file.txt
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# Print line if field 1 does NOT match regex in file.txt
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awk '$1 !~ /regex/' file.txt
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# Print lines with more than 80 characters in file.txt
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awk 'length > 80' file.txt
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# Print a multiplication table.
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awk -v RS='' '
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{
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for(i=1;i<=NF;i++){
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printf("%dx%d=%d%s", i, NR, i*NR, i==NR?"\n":"\t")
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}
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}
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' <<< "$(seq 9 | sed 'H;g')"
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# Specify output separator character.
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printf '1 2 3' | awk 'BEGIN {OFS=":"}; {print $1,$2,$3}'
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# Search paragraph for the given REGEX match.
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# Paragraphs will be collapsed together.
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awk -v RS='' '/42B/' file
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# Search paragraph for the given REGEX match.
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# Paragraphs will be separated with a new line.
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awk -v RS= ORS='\n\n' '/42B/' file
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# Display only first field in text taken from STDIN.
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echo 'Field_1 Field_2 Field_3' | awk '{print $1}'
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# Note that in this case, you're far better off using cut(1).
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# Use AWK solo; without the need for something via STDIN.
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awk 'BEGIN {print("Example text.")}'
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# Access environment variables from within AWK.
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awk 'BEGIN {print ENVIRON["LS_COLORS"]}'
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# Count number of lines taken from STDIN.
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free | awk '{L++} END {print(L)}'
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# Cleaner, more efficient approach to the above.
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free | awk 'END {print(NR)}'
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# Output unique list of available sections under which to create a DEB package.
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awk '!A[$1]++ {print($1)}' <<< "$(dpkg-query --show -f='${Section}\n')"
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# Using process substitution (`<()` is NOT command substitution), with AWK and
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# its associative array variables, we can print just column 2 for lines whose
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# first column is equal to what's between the double-quotes.
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awk '{NR != 1 && A[$1]=$2} END {print(A["Mem:"])}' <(free -h)
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# While below is an easier and simpler solution to the above, it's not at all
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# the same, and in other cases, the above is definitely preferable.
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awk '/^Mem:/ {print($2)}' <(free -h)
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# Output list of unique uppercase-only, sigil-omitted variables used in FILE.
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awk '
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{
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for(F=0; F<NF; F++){
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if($F~/^\$[A-Z_]+$/){
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A[$F]++
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}
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}
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}
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END {
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for(I in A){
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X=substr(I, 2, length(I))
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printf("%s\n", X)
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}
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}
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' FILE
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# Output only lines from FILE between PATTERN_1 and PATTERN_2. Good for logs.
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awk '/PATTERN_1/,/PATTERN_2/ {print}' FILE
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# Pretty-print a table of an overview of the non-system users on the system.
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awk -F ':' '
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BEGIN {
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printf("%-17s %-4s %-4s %-s\n", "NAME", "UID", "GID", "SHELL")
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}
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$3 >= 1000 && $1 != "nobody" {
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printf("%-17s %-d %-d %-s\n", $1, $3, $4, $7)
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}
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' /etc/passwd
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# Display the total amount of MiB of RAM available in the machine. This is also
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# a painful but useful workaround to get the units comma-separated, as would be
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# doable with Bash's own `printf` built-in.
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awk '/^MemTotal:/ {printf("%'"'"'dMiB\n", $2 / 1024)}'
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# It's possible to sort strings in AWK, as well as uniq-ing, meaning you can
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# replace uniq(1) and sort(1) calls with just the one call of AWK. Granted, you
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# can use `sort -u` to do both, but AWK offers much more functionality.
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#
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# Unlike when using AWK to uniq-ify, uniq(1) only works by adjacency, meaning
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# the duplicate lines must be adjacent to one another for them to be handled.
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awk '
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{
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!Lines[$0]++
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}
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END {
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asorti(Lines, Sorted)
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for (Line in Sorted) {
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print(Sorted[Line])
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}
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}
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' FILE
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# Remove duplicate lines
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awk '!seen[$0]++' file.txt
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# Remove all empty lines
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awk 'NF > 0' file.txt
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