In a bash-script I'd like to retrieve the last command which was executed. In bash itself the following command works like a charm.
lastCommand=$(echo `history |tail -n2 |head -n1` | sed 's/[0-9]* //')
Inside scripts however history doesn't work at all.
Is there a way to retrieve the command inside a script?
For bash v4+ :
Use interactive mode in shell.
Set she-bang as
#!/bin/bash -i
and history inside of your script will work.
$ cat test.sh
#!/bin/bash
history | wc -l
$ ./test.sh
0
$ sed -i '1s/bash/bash -i/' test.sh
$ ./test.sh
6495
Commands was executed inside of script are not recorded into history.
For bash v3 (and possible for older ones)
The way above doesn't work for this vesions of bash. However you can remove she-bang at all and history will work well. This way also works great for bash v4.
set she-bang as interactive and do not forget about set -o history like chepner mentioned.
#!/bin/bash -i
set -o historyPS. history |tail -n2 |head -n1 doesn't equal to the last command. it is command before last one.
Note if last or prelast commands were multiline it won't return the correct result.
btw in console you can use !-2 to refer to prelast command instead of your strange construction. unfortunately it seems doesn't work in shell script even in interactive mode.
-i, just use set -o history to specifically turn on history expansion in your script.
Does this help?
lastCommand=$(`cat ~/.bash_history |tail -n2 |head -n1` | sed 's/[0-9]* //')
Or maybe this:
echo !!
As bash have a build in facilities to provide last command
!! equal to the last command. However OP construction equals to the command just before the last one. !-2 exactly equals to OP construction. Unfortunately both !! and !-2 don't work inside of shell script.