((x++))

increment a bash variable


-1
By: takac
2011-09-13 09:27:58

These Might Interest You

  • I wrote this script to speed up Nginx configs. This (long) one liner can be run via BASH. You will see that we set a variable in bash called 'foo' and the streamline editor (sed) finds 'bar' in 'foo.conf' next it writes that output to a temp file (foo.temp) and removes the first 5 lines (that aren't needed in this case) & lastly it moves (overwrites) foo.temp to foo.conf Show Sample Output


    0
    variable="foo" && sed 's/bar/'$variable'/g' $variable.conf >> $variable.temp && sed '1,5d' $variable.temp && mv $variable.temp $variable.conf
    jdorfman · 2010-07-09 22:12:51 0
  • for exemple : var="echo hello"; $var this will display "hello" with bash with zsh, by default, this will make an error : "command not found : echo hello" hwordsplit option permit zsh to act like bash on this point


    0
    setopt shwordsplit
    Gentux · 2010-03-08 20:52:55 1
  • 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


    8
    set -eu
    wipu · 2010-04-07 11:54:40 2
  • I just found another use for the builtin ':' bash command. It increments counters for me in a loop if a certain condition is met... : [arguments] No effect; the command does nothing beyond expanding arguments and performing any specified redirections. A zero exit code is returned. Show Sample Output


    2
    [ $V ] || : $((V++)) && echo $V
    axelabs · 2012-06-15 16:48:03 0
  • Set a bookmark as normal shell variable p=/cumbersome/path/to/project To go there to p This saves one "$" and is faster to type ;-) The variable is still useful as such: vim $p/<TAB> will expand the variable (at least in bash) and show a list of files to edit. If setting the bookmarks is too much typing you could add another function bm() { eval $1=$(pwd); } then bookmark the current directory with bm p


    4
    to() { eval dir=\$$1; cd "$dir"; }
    hfs · 2010-10-15 13:40:35 3
  • I don't know why anyone would use this, I was just messing around tonight and managed to start bash without using any letters and thought I would share. It's pretty simple, first it tries to execute "-" redirecting stderr to stdout which prints the error "bash: -: command not found" to standard output, then I try to execute "bash: -: command not found" which produces the output "bash: bash: -: command not found: command not found". lastly, (on the other side of the semicolon) I use the underscore environment variable which refers to the last command run ("bash: -: command not found") and take out everything after the first ":" character using brace expressions and your left with "bash" Show Sample Output


    6
    "$(- 2>&1)";${_%%:*}
    LinuxMan · 2012-12-29 09:21:09 2

What Others Think

You could also do: let ++x But that's not really worth my fu.
h3xx · 348 weeks and 4 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

You must be signed in to comment.

What's this?

commandlinefu.com is the place to record those command-line gems that you return to again and again. That way others can gain from your CLI wisdom and you from theirs too. All commands can be commented on, discussed and voted up or down.

Share Your Commands



Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

» http://twitter.com/commandlinefu
» http://twitter.com/commandlinefu3
» http://twitter.com/commandlinefu10

Subscribe to the feeds.

Use your favourite RSS aggregator to stay in touch with the latest commands. There are feeds mirroring the 3 Twitter streams as well as for virtually every other subset (users, tags, functions,…):

Subscribe to the feed for: