How to show line number when executing bash script

In Bash, $LINENO contains the line number where the script currently executing.

If you need to know the line number where the function was called, try $BASH_LINENO. Note that this variable is an array.

For example:

#!/bin/bash function log() { echo "LINENO: ${LINENO}" echo "BASH_LINENO: ${BASH_LINENO[*]}" } function foo() { log "$@" } foo "$@" 

See here for details of Bash variables.

PS4 with value $LINENO is what you need,

E.g. Following script (myScript.sh):

 #!/bin/bash -xv PS4='${LINENO}: ' echo "Hello" echo "World" 

Output would be:

 ./myScript.sh +echo Hello 3 : Hello +echo World 4 : World 

Workaround for shells without LINENO

In a fairly sophisticated script I wouldn't like to see all line numbers; rather I would like to be in control of the output.

Define a function

echo_line_no () { grep -n "$1" $0 | sed "s/echo_line_no//" # grep the line(s) containing input $1 with line numbers # replace the function name with nothing } # echo_line_no 

Use it with quotes like

echo_line_no "this is a simple comment with a line number" 

Output is

16 "this is a simple comment with a line number" 

if the number of this line in the source file is 16.

This basically answers the question How to show line number when executing bash script for users of ash or other shells without LINENO.

Anything more to add?

Sure. Why do you need this? How do you work with this? What can you do with this? Is this simple approach really sufficient or useful? Why do you want to tinker with this at all?

Want to know more? Read reflections on debugging

You can use this shebang line at the top of individual scripts to enable extensive, colour-coded tracing of each command:

#!/usr/bin/env -S PS4='\\033[0;33m+(${BASH_SOURCE:-$0}:${LINENO}):\\033[0m ${FUNCNAME[0]:+${FUNCNAME[0]}(): }' bash -x 

This combines the comments from @Ulysse BN and @nikhilweee on this answer — and addresses @majorgear's comment on the same — with the arguably somewhat improved method of using env instead of bash directly in the shebang line.

The -S parameter on env allows the -x to be passed to bash.

If you're using $LINENO within a function, it will cache the first occurrence. Instead use ${BASH_LINENO[0]}

Simple (but powerful) solution: Place echo around the code you think that causes the problem and move the echo line by line until the messages does not appear anymore on screen - because the script has stop because of an error before.

Even more powerful solution: Install bashdb the bash debugger and debug the script line by line