Jurgen—Some basic Unix commands
Some basic Unix commands
Definitions
{arg} – required parameter
[arg] – optional parameter
path – a filename which may include the path to the file, i.e.:
file
subdir/file
../parentsubdir/file
/from/root/dir/file
cmd1; cmd2 – execute two commands, one after the other
cmd1 | cmd2 – use the output of cmd1 as the input of cmd2 (pipe)
cmd > path – save the output of cmd in a file
Commands
ls – list files in current dir
ls -a – list all files (including hidden files)
ls -l – list files in long format
ls [path] – list files at directory path, i.e. ls /usr/bin
cd [path] – change working directory to path
pwd – print current working directory
date – print current date
mkdir {path} – make a directory
rm {path} – delete a file
rmdir {path} – delete a directory
mv {spath} {dpath} – move or rename file at spath to dpath
mv {spath} [spath, …] {dpath} – move several files to dpath (where dpath must be an existing directory)
cat {path} – print contents of file
grep text [path] – print lines containing text in file (or if no file, standard input)
less {path} – display contents of file with navigation
wc [path] – count characters, words, and lines in file (or use “wc -l” for lines only)
head [path] – print first 10 lines of file (or “head -30” to print first 30 lines)
tail [path] – print last 10 lines of file
ps -ef – list all processes on system
Examples
Note that the following are two different ways of doing the same thing:
grep bailux /etc/passwd
cat /etc/passwd | grep bailux
Make a subdirectory called ‘pictures’ and move all files ending in ‘.jpg’ there:
mkdir pictures
mv *.jpg pictures
How many processes does user ‘bailux’ have executing?
ps -ef | grep bailux | wc -l