Commands by wipu

Commands by wipu (4)

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Suppress output of loud commands you don't want to hear from

This works even if there are spaces in any word in the command line. Show Sample Output
This is sample output - yours may be different.
```
quietly "/path that may contain spaces/command" "arg 1" "arg 2"
```
3

quietly() { "$@" > /dev/null 2>&1; }

wipu · 2011-10-04 06:45:42 5
Reproduce test failure by running the test in loop

If you need to fix a randomly failing test (race condition), you need to run it until you get that hard-to-reproduce failure. Show Sample Output
This is sample output - yours may be different.
```
Test run starting...
...
SUCCESS
Test run starting...
...
FAILURE
```
-3

(set -e; while true; do TEST_COMMAND; done) | tee log

wipu · 2011-09-06 12:29:11 5
Sum size of files returned from FIND

Just an alternative. Here the output of the subshell statement is a complete script for dc so you can save it, manipulate it with some other tool or just debug it with less.
This is sample output - yours may be different.
0

(echo 0; find [args...] -printf '%s +\n'; echo p) | dc

wipu · 2011-08-17 07:49:55 4
Robust expansion (i.e. crash) of bash variables with a typo

By default bash expands an unbound variable to an empty string. This can be dangerous, if a critical variable name (a path prefix for example) has a typo. The -u option causes bash to treat this as an error, and the -e option causes it to exit in case of an error. These two together will make your scripts a lot safer against typos. The default behaviour can be explicitly requested using the ${NAME:-} syntax. A (less explicit) variation: #!/bin/bash -eu Show Sample Output
This is sample output - yours may be different.
```
$ cat safe-cacheclean.sh 
#!/bin/bash

set -eu
CACHEDIR=mycache
# a dangerous-looking typo, is /bin going to disappear:
rm -rf "$CACHEDI/bin"

$ ./safe-cacheclean.sh 
./safe-cacheclean.sh: line 7: CACHEDI: unbound variable
```
8

set -eu

wipu · 2010-04-07 11:54:40 8

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paste one file at a time instead of in parallel

random xkcd comic

i sorta stole this from http://www.shell-fu.org/lister.php?id=878#MTC_form but it didn't work, so here it is, fixed. --- updated to work with jpegs, and to use a fancy positive look behind assertion.

Remove color codes (special characters) with sed

Removes ANSI color and end of line codes to the [{attr1};...;{attrn}m format.

Sort contents of a directory with human readable output

Show sizes of all files and directories in a directory in size order. $du -hs * | sort -hr for reverse order. Taken from http://serverfault.com/questions/62411/how-can-i-sort-du-h-output-by-size

list block devices

Shows all block devices in a tree with descruptions of what they are.

Display packages and versions on Debian/Ubuntu distrib

Need admin right to run dpkg-query

When was your OS installed?

Show time and date when you installed your OS.

5 Which Aliases

5 helpful aliases for using the which utility, specifically for the GNU which (2.16 tested) that is included in coreutils. Which is run first for a command. Same as type builtin minus verbosity $ alias which='{ command alias; command declare -f; } | command which --read-functions --read-alias' Which (a)lias $ alias whicha='command alias | command which --read-alias' Which (f)unction $ alias whichf='command declare -f | command which --read-functions' Which e(x)ecutable file in PATH $ alias whichx='command which' Which (all) alias, function, builtin, and files in PATH $ alias whichall='{ command alias; command declare -f; } | command which --read-functions --read-alias -a' # From my .bash_profile http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

continuously print string as if being entered from the keyboard

Cycles continuously through a string printing each character with a random delay less than 1 second. First parameter is min, 2nd is max. Example: 1 3 means sleep random .1 to .3. Experiment with different values. The 3rd parameter is the string. The sleep will help with battery life/power consumption. $ cycle 1 3 $(openssl rand 100 | xxd -p) Fans of "The Shining" might get a kick out of this: $ cycle 1 4 ' All work and no play makes Jack a dull boy.'

Edit a file inside a compressed archive without extracting it

If you vim a compressed file it will list all archive content, then you can pickup any of them for editing and saving. There you have the modified archive without any extra step. It supports many file types such as tar.gz, tgz, zip, etc.

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Commands by wipu (4)

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