mirror of
https://github.com/chubin/cheat.sheets
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52 lines
2.4 KiB
Plaintext
52 lines
2.4 KiB
Plaintext
# 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 a multiplication table
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seq 9 | sed 'H;g' | awk -v RS='' '{for(i=1;i<=NF;i++)printf("%dx%d=%d%s", i, NR, i*NR, i==NR?"\n":"\t")}'
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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 for a paragraph containing string
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awk -v RS='' '/42B/' file
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# display only first column from multi-column text
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echo "first-column second-column third-column" | awk '{print $1}'
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# Use AWK solo; without the need for something via STDIN.
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awk BEGIN'{printf("Example text.\n")}'
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# Accessing environment variables from within AWK.
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awk 'BEGIN{print ENVIRON["LS_COLORS"]}'
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# One method to count the number of lines; in this case, read from STDIN.
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free | awk '{i++} END{print i}'
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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($2)}' <(free -h)
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# Output list of unique uppercase-only, sigil-omitted variables used in [FILE].
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awk '{for(F=0; F<NF; F++){if($F~/^\$[A-Z_]+$/){A[$F]++}}} END{for(I in A){X=substr(I, 2, length(I)); printf("%s\n", X)}}' [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 -SPF ':' 'BEGIN {printf("%-17s %-4s %-4s %-s\n", "NAME", "UID", "GID", "SHELL")} $3>=1000 && $1!="nobody" {printf("%-17s %-d %-d %-s\n", $1, $3, $4, $7)}' /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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