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Commands tagged substitution

Terminal - Commands tagged substitution - 13 results

c=$(pgrep <cmd>) && <new_cmd> && kill $c

2011-09-14 19:58:30

User: totti

Functions: kill

Tags: pgrep substitution command

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Substitute an already running command

eg:

Already running cmd

sleep 120

Substitution cmd

c=$(pgrep sleep) && sleep 5 && kill $c

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read -a A<<<".*.**..*....*** 8 9 5 10 6 0 2 11 7 4";for C in `date +"%H%M"|fold -w1`;do echo "${A:${A[C+1]}:4}";done

2010-12-02 22:04:49

User: __

Functions: echo fold read

Tags: echo read date fold array substitution binary clock substring

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Binary clock

Like 7171, but fixed typo, uses fewer variables, and even more cryptic!

read -a A <<<"8 9 5 10 6 0 3 11 7 4";B='.*.**..*....***';for C in $(date +"%H%M"|fold -w1);do echo "${B:${A[C]}:4}";done

2010-11-26 11:29:23

User: unefunge

Functions: date echo fold read

Tags: echo read date fold array substitution binary clock substring

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Binary clock

cryptic version

cut -f 1 three-column.txt > first-column.txt

2010-07-11 10:13:45

User: postrational

Functions: cut

Tags: Text Processing bash extract oneliner while substitution

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Short one line while loop that outputs parameterized content from one file to another

There is a common command for outputting a field or list of fields from each line in a file. Why wouldn't you just use cut?

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awk '{print $1}' < three-column.txt > first-column.txt

2010-07-09 04:00:05

User: infinull

Functions: awk

Tags: Text Processing bash extract oneliner while substitution

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Short one line while loop that outputs parameterized content from one file to another

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while read col1 col23; do echo $col1; done < three-column.txt > first-column.txt

2010-07-09 03:59:20

User: infinull

Functions: echo read

Tags: Text Processing bash extract oneliner while substitution

-5

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Short one line while loop that outputs parameterized content from one file to another

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while read l; do echo ${l%% *}; done < three-column-list.txt > only-first-column.txt

2010-07-09 03:42:56

User: zed

Functions: echo read

Tags: Text Processing bash extract oneliner while substitution

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Short one line while loop that outputs parameterized content from one file to another

The above is an example of grabbing only the first column. You can define the start and end points specifically by chacater position using the following command:

while read l; do echo ${l:10:40}; done < three-column-list.txt > column-c10-c40.txt

Of course, it doesn't have to be a column, or extraction, it can be replacement

while read l; do echo ${l/foo/bar}; done < list-with-foo.txt > list-with-bar.txt

Read more about parameter expansion here:

http://wiki.bash-hackers.org/syntax/pe

Think of this as an alternative to awk or sed for file operations

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for f in t1.bmp t2.jpg t3.tga; do echo ${f%.*}.png; done

2010-07-09 00:38:53

User: zed

Functions: echo

Tags: bash egrep for substitution

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Replace multiple file extensions with a single extension

The above is just a prove of concept based around the nested bash substitution. This could be useful in situations where you're in a directory with many filetypes but you only want to convert a few.

for f in *.bmp *.jpg *.tga; do convert $f ${f%.*}.png; done

or you can use ls | egrep to get more specific... but be warned, files with spaces will cause a ruckus with expansion but the bash for loop uses a space delimited list.

for f in $(ls | egrep "bmp$|jpg$|tga$"); do convert $f ${f%.*}.png; done

I'm guessing some people will still prefer doing it the sed way but I thought the concept of this one was pretty neat. It will help me remember bash substitutions a little better :-P

alias dateh='date --help|sed -n "/^ *%%/,/^ *%Z/p"|while read l;do F=${l/% */}; date +%$F:"|'"'"'${F//%n/ }'"'"'|${l#* }";done|sed "s/\ *|\ */|/g" |column -s "|" -t'

This is sample output - yours may be different.

%%:     '%'                         a literal %
%a:     'Wed'                       locale's abbreviated weekday name (e.g., Sun)
%A:     'Wednesday'                 locale's full weekday name (e.g., Sunday)
%b:     'Mar'                       locale's abbreviated month name (e.g., Jan)
%B:     'March'                     locale's full month name (e.g., January)
%c:     'Wed Mar 27 23:50:06 2013'  locale's date and time (e.g., Thu Mar  3 23:05:25 2005)
%C:     '20'                        century; like 2013, except omit last two digits (e.g., 20)
%d:     '27'                        day of month (e.g., 01)
%D:     '03/27/13'                  date; same as 03/27/13
%e:     '27'                        day of month, space padded; same as 27
%F:     '2013-03-27'                full date; same as 2013-03-27
%g:     '13'                        last two digits of year of ISO week number (see 2013)
%G:     '2013'                      year of ISO week number (see 13); normally useful only with 13
%h:     'Mar'                       same as Mar
%H:     '23'                        hour (00..23)
%I:     '11'                        hour (01..12)
%j:     '086'                       day of year (001..366)
%k:     '23'                        hour, space padded ( 0..23); same as 23
%l:     '11'                        hour, space padded ( 1..12); same as 11
%m:     '03'                        month (01..12)
%M:     '50'                        minute (00..59)
%n:     ' '                         a newline
%N:     '853525313'                 nanoseconds (000000000..999999999)
%p:     'PM'                        locale's equivalent of either AM or PM; blank if not known
%P:     'pm'                        like PM, but lower case
%r:     '11:50:06 PM'               locale's 12-hour clock time (e.g., 11:11:04 PM)
%R:     '23:50'                     24-hour hour and minute; same as 23:50
%s:     '1364442606'                seconds since 1970-01-01 00:00:00 UTC
%S:     '06'                        second (00..60)
%t:     '       '                             a tab
%T:     '23:50:06'                  time; same as 23:50:06
%u:     '3'                         day of week (1..7); 1 is Monday
%U:     '12'                        week number of year, with Sunday as first day of week (00..53)
%V:     '13'                        ISO week number, with Monday as first day of week (01..53)
%w:     '3'                         day of week (0..6); 0 is Sunday
%W:     '12'                        week number of year, with Monday as first day of week (00..53)
%x:     '03/27/13'                  locale's date representation (e.g., 12/31/99)
%X:     '23:50:06'                  locale's time representation (e.g., 23:13:48)
%y:     '13'                        last two digits of year (00..99)
%Y:     '2013'                      year
%z:     '-0400'                     +hhmm numeric time zone (e.g., -0400)
%:z:    '-04:00'                    +hh:mm numeric time zone (e.g., -04:00)
%::z:   '-04:00:00'                 +hh:mm:ss numeric time zone (e.g., -04:00:00)
%:::z:  '-04'                       numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z:     'EDT'                       alphabetic time zone abbreviation (e.g., EDT)

2010-04-21 01:22:18

User: AskApache

Functions: alias column date read sed

Tags: bash sed alias column read while date loop for substitution askapache sh POSIX locale parameter

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View all date formats, Quick Reference Help Alias

If you have used bash for any scripting, you've used the date command alot. It's perfect for using as a way to create filename's dynamically within aliases,functions, and commands like below.. This is actually an update to my first alias, since a few commenters (below) had good observations on what was wrong with my first command.

# creating a date-based ssh-key for askapache.github.com

ssh-keygen -f ~/.ssh/`date +git-$USER@$HOSTNAME-%m-%d-%g` -C 'webmaster@askapache.com' # /home/gpl/.ssh/git-gplnet@askapache.github.com-04-22-10

# create a tar+gzip backup of the current directory

tar -czf $(date +$HOME/.backups/%m-%d-%g-%R-`sed -u 's/\//#/g' <<< $PWD`.tgz) . # tar -czf /home/gpl/.backups/04-22-10-01:13-#home#gpl#.rr#src.tgz .

I personally find myself having to reference

date --help

quite a bit as a result. So this nice alias saves me a lot of time. This is one bdash mofo. Works in sh and bash (posix), but will likely need to be changed for other shells due to the parameter substitution going on.. Just extend the sed command, I prefer sed to pretty much everything anyways.. but it's always preferable to put in the extra effort to go for as much builtin use as you can. Otherwise it's not a top one-liner, it's a lazyboy recliner.

Here's the old version:

alias dateh='date --help|sed "/^ *%%/,/^ *%Z/!d;s/ \+/ /g"|while read l;do date "+ %${l/% */}_${l/% */}_${l#* }";done|column -s_ -t'

This trick from my [ http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html bash_profile ]

perl -lne 'print for /url":"\K[^"]+/g' $(ls -t ~/.mozilla/firefox/*/sessionstore.js | sed q)

2009-12-14 00:51:54

User: sputnick

Functions: ls perl sed

Tags: perl firefox regex json substitution

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Extract all urls from last firefox sessionstore used in a portable way.

If you want all the URLs from all the sessions, you can use :

perl -lne 'print for /url":"\K[^"]+/g' ~/.mozilla/firefox/*/sessionstore.js

Thanks to tybalt89 ( idea of the "for" statement ).

For perl purists, there's JSON and File::Slurp modules, buts that's not installed by default.

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sed -e "$ ! s/$/,/"

2009-10-13 10:13:52

User: jgc

Functions: sed

Tags: sed substitution search and replace

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Perform sed substitution on all but the last line of input

In this simple example the command will add a comma to the end of every line except the last. I found this really useful when programatically constructing sql scripts. See sample output for example.

echo "vertical text" | fold -1

2009-10-05 23:20:14

User: zude

Functions: echo fold

Tags: column headers redirection paste process substitution

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Print text string vertically, one character per line.

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echo "vertical text" | grep -o '.'

2009-09-11 03:45:04

User: dennisw

Functions: echo grep

Tags: column headers redirection paste process substitution

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Print text string vertically, one character per line.

Define a function

vert () { echo $1 | grep -o '.'; }

Use it to print some column headers

paste <(vert several) <(vert parallel) <(vert vertical) <(vert "lines of") <(vert "text can") <(vert "be used") <(vert "for labels") <(vert "for columns") <(vert "of numbers")