View Source: TwoLetterCommands - Waikato Linux Users Group

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Two letter commands commonly found in Unix.

[Unix] has a reputation for having cryptic commands and syntax.
Commands marked with * are not as common, or are not so standard (ie distributed with a typical system).''Disclaimer'' - this is based on personal observation of unix systems, and is in no way definitive.

| ar(1) | archive tool
| as(1) | assembler
| at(1) | run commands AT a certain time
| bc(1) | arbitrary precision calculator
| cd(1) | Change Directory (now a builtin)
| cp(1) | copy
| dc(1) | desk calculator
| dd(1) | copy blocks between files/devices
| df(1) | report Disk Free
| du(1) | report Disk Usage
| ed(1) | EDitor
| gs(1) * | GhostScript (postscript interpreter)
| gv(1) | GhostView (postscript viewer) (X based)
| id(1) | prints user ID
| ld(1) | linker
| ln(1) | create symbolic !LiNks
| lp(1) | send file to (Line) Printer
| ls(1) | !LiSt directory
| m4(1) * | m4 language processor
| mt(1) | Magnetic Tape control
| mv(1) | !MoVe files
| nm(1) | extract symbols from objects
| od(1) | print Octal Dump of files
| ps(1) | print Process Status
| pr(1) | paginate input for PRinting
| rm(1) | !ReMove files
| rn(1) | Read News
| sc(1) * | Spreadsheet Calculator
| sh(1) | SHell
| sq(1) * | SQueeze a sorted list
| su(1) | Switch User (or Super User)
| tr(1) | TRanslate (swap) characters
| vi(1) | VIsual Editor
| wc(1) | Word Count


''Since ls(1) is such an often-used and occasionally mistyped command, there's an amusing little program '[sl|http://gar.lnx-bbc.org/cvs/gar/games/sl/]' which does an animated Steam Loco.. It comes with freeBSD but there's probably a Linux port if you're really interested. - zcat'' (sl is in debian. But if you're like me the novelty will wear off pretty quickly as you can't use your terminal for a few seconds until the Steam Locomotive has gone across it).

The following command will list all TwoLetterCommands on your system:

 find {,/usr}/{,s}bin -type f | grep "/..$"

It looks in /bin, /usr/bin, /sbin, /usr/sbin for all files which have two letters in their name. On my Debian Woody system there are a number of ones not listed above, which are mainly just improved tools: lc is an improved wc, gw is a gnome version of 'w' (so thats a OneLetterCommand really... ;)

''The above is wrong (or at least bad) in so many ways. It has a useless use of grep(1); find(1) can already match globs, so just tell it to look for __-name '??'__. It will recurse directories and find files not available for direct invocation (at least the [GNU] version of find(1) has __-maxdepth__ which can be used to fix this). It will also find files without execution permission. The following is much more precise.'' --AristotlePagaltzis

 find ${PATH//:/ } -type f -name '??' -maxdepth 1 -perm +o+x

 # if you don't have a bash-ish shell you need an extra process:
 find `echo $PATH | tr : ' '` -type f -name '??' -maxdepth 1 -perm +o+x
3 pages link to TwoLetterCommands:
Last edited on Thursday, January 8, 2004 2:06:45 pm by AristotlePagaltzis
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