Monthly Archives: June 2012

UNIX-1.11 zip, basename, mktemp, script and rcs commands

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zip -r filename.zip file1 file2 file3 – zip and compress files, recursively
unzip filename.zip – unzip a zip file
rmdir dirname – remove empty directory
basename fullpath – returns the file or directory name
dirname fullpath – returns the directory
mktemp – creates a temporary file and outputs temp filename
factor number – list the factors of a number
script -a script.out – starts recording your output screen, ctrl+D to stop recording
kill %% – kills previous command
sudo apt-get install rcs – to install linux revision control system (RCS)
mkdir RCS – create a directory called RCS to store all versions of file
ci script.sh – checks in a file, file is not readable until checked out
ci -u script.sh – checks in a file, file is visible for others to read
co -l script.sh – checks out a file, holds the lock.
co -lr1.1 script.sh – checks out a version of file, holds the lock
rcsdiff script.sh – compares current file with latest checked in version
rcsdiff -r1.1 -r1.2 script.sh – compares version 1.1 and 1.2
which command – tells you where such command resides in
locate keyword – searches for files or paths that contains keyword (that are accessible to you)

UNIX-1.10 Customize Command Prompt

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set -o vi – puts your command prompt into VI mode, allows you to execute VI commands
/command – search for command history, n for next match found, N for previous match found
PS1 – variable that holds text of your prompt
PS1=”\H” – displays host name
PS1=”\s” – name of shell
PS1=”\u” – current username
PS1=”\w” – current working directory
PS1=”\@” – current time
PS1=”[\\u@\\H \\W \\@]\\$” – try this
PS1=”\e[x;ym$PS1\e[m” – \e[ starts the color mode, x;ym specifys color, \e[m ends color mode. x;y can be 0;30 to 0;37
case $(id -u) in
0) PS1=”${PS1}# “;;
*) PS1=”${PS1}$ “;;
esac
alias name=”command -options” – creating alias/shortcut commands
alias vi=’vim’
alias ls=’ls -F’
alias ll=’ls -l’
alias la=’ls -la’
alias cp=’cp -ip’
alias mv=’mv -i’

UNIX-1.8 ps, netstat, kill, pidof, fuser, awk commands

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ps -fu username – displays all processes started by user
ps -ef – display all processes running
ps -ef | grep ‘pname’ – look for specific process
netstat -t – see all tcp connections
netstat -an – see all network connections
netstat -c – netstat will execute every second
netstat -p – display processes that use these connections
kill pid – kills process by pid
kill -9 pid – force kill process by pid
& – execute process in background
free – show memory usage, alternatively use top
pidof command – shows process id for running process/command
fuser -vu dir – displays all processes that are using dir, along with owner id of processes
echo “hello world” | awk ‘{ print length($1) }’ – prints length of field
echo “hello world” | awk ‘{ print substr($1, 3) }’ – prints llo, substring function
echo “hello world” | awk ‘{sub(regex, replacement); print}’ – replace pattern on line and print
echo “HELLO world” | awk ‘{ print tolower($1) }’ – lower case field 1
echo “hello world” | awk ‘{ print toupper($1) }’ – upper case field 1

UNIX-1.7 Find Command

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find . -iname ‘regex’ – find filenames that match regex, case insensitive
find . -mtime +2 – find files that were modified 2 days ago or older
find . -mtime -2 – find files that were modified within past 2 days
find . -ctime +2 – find files that were created 2 days or older
find . -atime +2 – find files that were accessed 2 days or older
find . -cmin +30 – find files that were created 30 minutes ago or older
find . -mmin +30 – find files that were modified 30 minutes ago or older
find . -empty – find empty files or directory
find . -executable – find files that are executable by user
find . -readable – find files that are readable by user
find . -writable – find files that are writable by user
find . -size filesize – find files that have specified filesize (c = byte, k = kb, M = Mb, G = Gb)
find . -type filetype – find by file type (d = directory, f = file, l = link)
find . -user username – find files owned by user
find . -group groupname – find files that belong to specific group
find . -name ‘regex’ -delete – remove files that match regex
find . -name ‘regex’ -exec command – execute command on files found
find . -name ‘regex’ -ok command – same as -exec, but prompts for user’s input

UNIX-1.6 grep, useradd, usermod commands

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last -10 username – get last 10 logins of specific user
passwd – change password
diff -y file1 file2 – find differences between 2 files
grep ‘regex’ file – search for pattern
grep -i ‘regex’ file – case insensitive search
grep -P ‘regex’ file – full support of Perl regex
grep -e ‘regex1’ -e ‘regex2’ file – search for multiple patterns
grep -v ‘regex’ file – inverse of search pattern (return non-matching lines)
grep -n ‘regex’ file – display line number with search result
grep -B4 ‘regex’ file – also display 4 lines before match
watch -n5 command – executes command every 5 second
adduser username – add a new user
usermod username -d /home/newhome – change home for new user
usermod username -d /home/newhome -m – change and move home content to a new home
usermod username -e 2022-05-11 – set account expiration date
usermod username -g group_name – set user group name/id
usermod username -l new_username – change username for user
usermod username -p new_password – change password for user
usermod username -s shell_name – change default shell for user
sudo -u username -i – run future commands as another user