Bash One-Liners

A collection of practical or just pure awesome bash one-liner shell script tips with explanations

[Bash One-Liners @bashoneliners]

Download a URL with cookies set on the command line with curl: curl -b "session=$session" 'https://t.co/I5veJwHZnX'; https://t.co/afIT4oO1EG #bash #linux

[Bash One-Liners @bashoneliners]

Print the lines of file2 that exist in file1: grep -xFf file1 file2; https://t.co/v5mtJaBWFz #bash #linux

[Bash One-Liners @bashoneliners]

Extract regex capture groups using [[ and BASH_REMATCH: text='3 blue; 5 green'; [[ $text =~ ([0-9]+)" "(blue|green) ]] && { echo "count = ${BASH_REMATCH[1]}"; echo "color = ${BASH_REMATCH[2]}"; }; https://t.co/bKejI2boaH #bash #linux

[Bash One-Liners @bashoneliners]

Count the lines of each file extension in a list of files: git ls-files | xargs wc -l | awk -F ' +|\\.|/' '{ sumlines[$NF] += $2 } END { for (ext in sumlines) print ext, sumlines[ext] }'; https://t.co/jcJdpIMjub #bash #linux

[Bash One-Liners @bashoneliners]

Truncate a file or create an empty file: > /path/to/file; https://t.co/Qy98Udrtjf #bash #linux

[Bash One-Liners @bashoneliners]

Print the paths in $PATH sorted by line length: echo "${PATH//:/\\n}" | awk '{print length, $0}' | sort -n | cut -f2- -d' '; https://t.co/nbyaBqyY3o #bash #linux

[Bash One-Liners @bashoneliners]

Print lines of a file that don't exist in another file, ignoring the first two fields: awk -F'|' 'NR == FNR { $1 = ""; $2 = ""; seen[$0]++ } NR != FNR { orig = $0; $1 = ""; $2 = ""; if (!seen[$0]) print orig }' first.txt second.txt; https://t.co/Gw3cYWdsfY #bash #linux

[Bash One-Liners @bashoneliners]

Use inverted conditions with the find command: find . -type f -not -name '*.mp3'; https://t.co/0NLMPa2N8F #bash #linux

[Bash One-Liners @bashoneliners]

Replace a pattern in a file in a portable way: f=/path/to/file; sed -e "s/pattern/replacement/" "$f" > "$f".bak && mv "$f".bak "$f"; https://t.co/Y885ncXUMx #bash #linux

[Bash One-Liners @bashoneliners]

Generate a sequence of numbers using Brace Expansion: for i in {1..10}; do echo "$i"; done; https://t.co/YcBkM9ZTbx #bash #linux

[Bash One-Liners @bashoneliners]

Print the first 100 characters of a file: head -c 100 /path/to/file; https://t.co/qpYNOR1qyu #bash #linux

[Bash One-Liners @bashoneliners]

Pretty-print JSON with Python: curl -s 'https://t.co/UtqU616PjY' | python -m json.tool; https://t.co/4TYzMRt489 #bash #linux

[Bash One-Liners @bashoneliners]

Generate a sequence of numbers: seq 1 10; https://t.co/R5yy8gpVrc #bash #linux

[Bash One-Liners @bashoneliners]

Send an HTTP POST request as if submitting an HTML form using curl: curl --data "title=recipe&text=steps123" https://t.co/5u3kR4k08p; https://t.co/nYoFaTwmeo #bash #linux

[Bash One-Liners @bashoneliners]

Printing with jq multiple values in CSV or TSV formats: curl -s 'https://t.co/UtqU616PjY' | jq -r '.[] | [.id, .name, .stargazers_count] | @csv'; https://t.co/U4DrI3JFFG #bash #linux

[Bash One-Liners @bashoneliners]

List docker log sizes: docker ps -qa | xargs docker inspect --format='{{.LogPath}}' | xargs sudo du -hl; https://t.co/Gs54VBX9n9 #bash #linux

[Bash One-Liners @bashoneliners]

Display the number of connections per IP to port 80: while true; do clear; date; echo; echo "[Count] | [IP ADDR]"; echo "-------------------"; netstat -n | grep ':80\>' | awk '! /LISTEN/ {print $5}' | cut -d: -f1 | uniq -c; sleep 5; done; https://t.co/ngSchKARKR #bash #linux

[Bash One-Liners @bashoneliners]

Move file and cd with one command: mv file dir/ && cd "$_" && pwd; https://t.co/CKsILU8T1X #bash #linux

[Bash One-Liners @bashoneliners]

Check if a version string is in valid SemVer format: re_semver=...; perl -wln -e "/$re_semver/ or exit(1)" <<< "$version"; https://t.co/u0I8OmFudl #bash #linux

[Bash One-Liners @bashoneliners]

Print raw values with jq -r: echo '{"foo": "bar \" baz"}' | jq -r .foo; https://t.co/8iTp6f1HfQ #bash #linux