Linux Commands For Beginners

TL;DR

• Basic Linux commands that we use literally all the time.

alias

alias grep=“grep –color” alias

ps

• print pid: ps -C {program-name} -o pid=
• Show full command: ps -f | less
  • ps detects the size of your terminal window and clips to that.

xargs

• use \0 as the delimiter and -0 to use it
  • printf ‘%s\0’ Hello Hola Bonjour | xargs -0 -I _ echo _ Landon

Search

Sort files by date then grep

• ls -rt *.log | xargs grep -l

# Find which jar contains the class
find . -name "*.jar" | xargs grep Hello.class

List open files

• ls -l /proc/${pid}/fd
  • Use this when lsof is not installed
• lsof -p ${pid}

watch

• watch -n 5 curl -s localhost:8983/show/health
• -d: highlights the changes

curl

• –max-time

pbcopy (take standard input to clipboard) + pbpaste (take data from clipboard to standard output)

pbcopy < file.txt
ps aux | pbcopy
pbpaste > pastetest.txt

diff

diff -x '*.foo' -x '*.bar' -x '*.baz' -rq /destination/dir/1 /destination/dir/2

sed

• sed -n ‘16224,16482p’ filename > newfile

System

Check the age of the system

• rpm -qi basesystem | grep “Install Date”

Misc

• cd $(dirname ${file_full_path})
• tar xfz somefilename.tar.gz
• dirname, basename, realpath
• Copy one file to multiple file names
  • cat 1.ods | tee {jan,feb,mar}-{Rep,graph}.ods >/dev/null
• tail -f **/*.log

Get current working directory of a process

• pwdx
• lsof -p | grep cwd
• readlink -e /proc//cwd ##### [View a range of bash history]
• fl -l ${start} ${end}
• history | sed ‘start,{end}p’

Brace expansion

• mkdir -p {f1, f2}
• for i in {1..3}; do echo $i; done
  • {START..END..INCREMENT}

Command History

!!:n	where n is the 0-based position of the argument you want
!$	last argument from previous command
!^	first argument (after the program/built-in/script) from previous command
!!	previous command (often pronounced “bang bang”)
!n	command number n from history
!pattern	most recent command matching pattern
!!:s/find/replace	last command, substitute find with replace
:p	print the command - !!:p, !!n:p

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