Bash – How to Save Last Line Output from Terminal in Bash Script

bashscriptingshellshell-scripting

I am writing a bash script in which I would like to save the output of the last command in to a variable before running my next one so I can display it later.

I have tried a few different methods using tail with no success.

Any help will be very appreciated.

Best Answer

You can save the output of your last command to a temporary file, using tee.

TMPPFILE=$( mktemp );
echo "First command" | tee ${TMPFILE};
echo "Second command" | tee ${TMPFILE};
echo "Third command" | tee ${TMPFILE}

Then:

cat ${TMPFILE}     ## Should produces the line below
Third command

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Linux – Bash: how to know if the last command’s output ends with a newline or not

I've been experimenting with the following to emulate the feature from zsh in Bash:

$ unset PROMPT_SP; for ((i = 1; i <= $COLUMNS + 52; i++ )); do PROMPT_SP+=' '; done
$ PS1='\[\e[7m%\e[m\]${PROMPT_SP: -$COLUMNS+1}\015$ '

It issues a reverse video percent sign, followed by a bunch of spaces to make it wrap to the next line, then a carriage return, followed by a dollar sign and a space. You can add prompt escapes after the "\015" to customize your prompt.

Using this depends on how your terminal handles right margin line wrapping (automatic margins). The length of PROMPT_SP is arbitrary, but should be at least 80 or whatever your usual terminal width is. You may need to hard-code that value if $COLUMNS isn't set yet by the time the for loop is run in ~/.bashrc. You may want shopt -s checkwinsize if it's not already set.

Linux – bash : “set -e” and check if a user exists make script exit

You could always do something like below. Basically disabling the exit checking around the command you are running.

#!/bin/bash
set -e # eanble exit checking
lorem ipsum 
dolor sit amet
# temp disable exit checking
set +e
grep "^${USER}:" /etc/passwd
set -e
consectetur adipiscing elit

Best Answer

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