Cheat Sheet

Processes  tail [-n N] file – display last N

lines of file
View  cut –d delimiters –f fields – select
 ps [-e] [-f] - show processes “colums” from an input text
information  tr char1 char2 – change char1 to
Storage E.g.: ps –ef ; ps aux; ps –u root –f char2
 pstree [-a] [-p] [pid]  tr [-s] [-d] char – squeeze or
Partitioning delete character
 fdisk /dev/sdb –partitioning utility Interact  wc [-l] [-w] [-c] – count
 mkswap device_file  kill –l – show available signals lines/words/characters
- swapon device_file
 kill [–s signalName] pid – send
- swapoff [device_file] Bash operators
signal signalName to process pid
 kill [–signalNumber] pid
File systems
 kill all [-s signal] name – send  Chaining:
 mkfs –t fs_type device_file
signal to all process name - Sequence: ;
E.g.: mkfs –t ext4 /dev/sdb2 - Parallel execution: &
 jobs – show jobs
 mount –t fs_type [-o options] - Conditional execution: &&,||
device_file mount_point  fg [job_number] – bring job
job_number to foreground  Pipelines: |, |&
E.g.: mount –t ext4 /dev/sdb3 /mnt/data
 bg [job_number] – send job  Input/Output redirection
 umount device_file / umount - Redirecting input: <,<<,<<<
job_number to background
mount_point - Redirecting output:
Users >,>>,2>,2>>,&>,&>>
File and directory operations
 ls file – show information about Scripting
file or folder Create
Note: By default, a script returns 0
 cp [options] source destination  useradd –d HOME_DIR –m –s SHELL –g
E.g.: cp file1 file2 ; cp –r dir1 dir2 GROUP USERNAME
 if condition1;
 mv source destination  adduser username then
 rm [-r] file – use –r option to Note: adduser only valid in Debian commands
delete non empty folders [ elif condition2;
E.g.: rm file1 ; rm –r dir1 Mod then
 cd path – change working directory  usermod (similar arguments as commands]
to path useradd) [ else
 mkdir dir – create directory E.g.: usermod –d /localhome/sqa sqa commands]
fi
 rmdir dir – remove directory (only
if directory is empty) Delete
 userdel username E.g: if [ $a –lt 10 ] – value of a is less
 df – “disk free” show available than 10
space  deluser username
if [ $str1 = $str2 ] – test if two
 du – “disk usage” show used space strings are equal
Switching users: su [-] username
File security  for member in list;
Using the shell do
 chown user:group file – change file commands
owner  cat [-n] file1 file2 … - concatenate done
 chmod permissions file – change file multiple files
permissions  tac [-n] file1 file2 …  while condition;
E.g.: chmod 777 file.txt; chmod u=rwx,g=rx,o=rx  sort [-u] [-r] [-n] [file] do
file.txt ; chmod +x file.txt  head [-n N] file – display first N commands
lines of file done