Linux Tips and Tricks

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Unix/Linux Commands to Know and Cherish (with many thanks to Steve Lantz, CAC)

Shell: bash or tcsh
- The shell defines many of the commands you enter at the command line
- The Bourne Again Shell is an update to the original Bourne shell (sh)
- Similarly tcsh is an update to csh, the C Shell (up-arrow to get last command)
man = “manual” = the way you get help, e.g., “man ls”
Working with directories: cd, pwd, ls, mkdir, rmdir
- cd to change directory (popd, pushd to use directory stack); “cd ..” = up one level
- pwd = print working directory = print your current location (also known as .)
- “ls -l” gives you complete directory listing, “ls -a” lets you see .prefix-files
- mkdir to create a new directory, rmdir to remove an existing one
Environment variables: export (bash, sh) or setenv (tcsh, csh)
- Variables that are local to the shell are defined with “set”
- Env variables are inherited by shells started in the parent shell
- Type “set” to see locals, “env” to see environment
To view an environment variable: “echo $varname”
- PATH - list of directories to search when you ask the shell to run a program
- LD_LIBRARY_PATH - list to search for shared libraries
To add a directory to the path: “export PATH=$PATH:/opt/intel/bin”
Move, copy, remove files: mv, cp, rm
To view the contents of a file: “cat filename”
- cat = “concatenate to standard output”, stdout is the terminal by default
Redirect stdout using symbols
- “cat file1 > file2” replaces (clobbers) file2 with the contents of file1
- “cat file1 >> file2” appends file2 with the contents of file1
- “cmd1 | cmd2” to pipe stdout of cmd1 to stdin of cmd2
Text editors: nano, vi, emacs
- Terminal window becomes plain text editor
- No graphical interface, all editing done via special key sequences
Controlling processes
- control sequences: ctrl-c = kill, ctrl-z = suspend
- bg to put process in background, fg to bring to foreground, “jobs” to see bg list
For more tips and tricks...
- Introduction to Bash Shell
- Advanced Bash Scripting Guide