Bash – Splitting bash command line argument

bashshell-scriptstring

Is this the best way to split up a colon separated bash command line argument?

#!/bin/bash
hostlist=`echo $1| awk '{split($0,Ip,":")} END{for (var in Ip) print Ip[var];}'`
for host in $hostlist
 do
  ....
 done

Best Answer

Another way would be to use IFS, the shell's built-in method to split strings into fields.

OLDIFS=$IFS
IFS=':'
set -f
for host in $hostlist; do
  set +f
  echo "$host"
done
set +f
IFS=$OLDIFS

set -f turns off filename generation (globbing): without it, wildcards *?\[ would be expanded in each word.

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Bash – Delete whole argument in current bash command-line

Bash has readline commands that aren't bound by default. You can find them at reference: http://www.gnu.org/software/bash/manual/html_node/Bindable-Readline-Commands.html#Bindable-Readline-Commands

The command you are looking for is called shell-backward-kill-word. You have to select a shortcut first. Let's use Ctrlp, since it's "previous command" - same as up arrow.

bind '"\C-p": shell-backward-kill-word'

Bash script command line argument to upper case

Let's start with this test script:

$ cat script.sh 
GUARD=${1^^}
echo $GUARD

This works:

$ bash script.sh abc
ABC

This does not work:

$ sh script.sh abc
script.sh: 1: script.sh: Bad substitution

This is because, on my system, like most debian-like systems, the default shell, /bin/sh, is not bash. To get bash features, one needs to explicitly invoke bash.

The default shell on debian-like systems is dash. It was chosen not because of features but because of speed. It does not support ^^. To see what it supports, read man dash.

Best Answer

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Bash script command line argument to upper case

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