The following tables lists useful commands (for developers) in Unix and its many (GNU) Linux flavours. Use man <commandname> to find out more... |
|
Tool/Usage |
Description |
|---|---|
at |
Run command at a particular time |
| awk [-f <script>] <files> | Pattern-matching text-processing language |
| bc | Command-line calculator (actually rather more than that) |
| cat <files> | Just like MS-DOS's TYPE command |
| cmp | Fast diff for binary files |
| compress <files> | Packs a file and appends .Z to the filename (e.g. "compress *.backup") |
| cut <options> <files> | Cuts specific columns from text file (e.g. "cut -c 12-21") |
| df <paths> | Gives space left on disk (e.g. "df .") |
| dircmp | Directory contents comparison |
| du <paths> | Gives space used by files directories (e.g. "du ~") |
| expr | Allows arithmetic to be performed in a script |
| fastboot <options> | Reboots machine (if logged-in as root), e.g. "fastboot -l" |
| file <files> | Displays guessed type for the supplied file |
| find <paths> <expression> | Searches for files that meet criteria (e.g "find . -name STRING -print") |
| fold | Perform word-wrapping at a specified column (default 80) |
| grep <pattern> <files> | Search for occurences of a string (or just counts occurences with -c option) |
| head <options> <files> | Lists first n lines of a file (e.g. "head -4 ada.lib") |
| hostname | Returns this machine name |
| join | Merge lines from files matching first column |
| kill [-s <signal>] <pid> | Kills off a proces by process ID (or kill -l to list signals) |
| line | Used as a pausing point in a script |
| ln | Creates a symbolic file link (e.g. "ln -s ACTUAL_PATH LINK_NAME") |
| lpstat | Prints output status of all printers (e.g. "lpstat -o") |
| nice <command spec> | Runs command with lower priority |
| nohup <command spec> | Carries command on even after log-out |
od <files> |
Displays the contents of a data file in octal (or hex using -X) |
| paste | Merge lines from files in columns |
pmap <pid> |
Shows memory usage of shared libraries |
| ps <options> | Displays process statuses (e.g. "ps -auxww | more") |
| rsh <hostname> <command> | Runs a single command on another computer (e.g. "rsh poplar ps -aux") |
| script | Records all shell I/O to file (CTRL-D to stop) |
| sdiff | Visually displays file differences (e.g. "sdiff file file2 | more") |
| sed | Stream line editor |
| sort | Sorts a text-file. -u removes duplicates (e.g. "who | sort -u") |
strace <command> |
System-call tracer |
| stty | Set terminal options |
| tail <options> <files> | Lists last n lines of a file (e.g. "head -4 ada.lib") |
| tar | Archives (tar -cf *.a) and de-archives (tar -xf TAR_FILE) |
| tee | Copies input to file as well as to screen |
top |
Continuously displays the most CPU intensive processes |
| tr | Replaces all occurences of one character with another |
| trace | Follows all system-calls for a (non-shell) command |
| uname | Prints Unix version (e.g. "uname -ru") |
| umask | Sets default file permissions using octal (e.g. "umask 022") |
| vi | Fast but unfriendly text editor favoured by "guru" programmers |
vmstat |
Reports a summary of system utilisation |
| wc | File word count (wc -w <filename>) or line count (wc -l filename) |
| who | Lists users currently logged-in to a machine |
| whoami | Returns current user name |
| xargs | Creates a list of filenames to run a particular file on |
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