koalaman
request: warn SC2103 on popd
SC2103 is: "Use a ( subshell ) to avoid having to cd back."
cd home
cd - # warns SC2103
pushd home
popd # doesn't warn SC2103, but should imo
@bugsbugsbux can you elaborate why you want this? From my understanding, the cd in a shell script can cause side effects outside the script. So you always need to cd back to avoid this. As far as I know, this is not the case with pushd/pops. Hence there is no warning needed.
When I filed this issue I thought SC2103 was a hint to avoid a bad pattern, which I would have liked to know about before writing lots of pushd /; do-sth; popd and only came across when I used cd /; do-sth; cd - instead in some other script.
the cd in a shell script can cause side effects outside the script. So you always need to cd back to avoid this.
I don't think so: If you put cd / or pushd / in a script and execute it with bash myscript.sh or ./myscript.sh you end up where you started, on the other hand if you source any of the two scripts you end up in /.
Both, popd and cd - can fail or produce unexpected outcomes: cd - always fails before the first directory change (but not afterwards because it just switches back and forth between the current and previous folders) "-bash: cd: OLDPWD not set", popd always fails if there is no previous entry in the directory stack "-bash: popd: directory stack empty". Both commands should be conditional on the success of the corresponding previous directory change; or better avoided alltogether as SC2103 suggests.
IMO, it's best to rely as little as possible on the filesystem. It can be changed by some other process during script execution, is one reason. If it's necessary, a data directory with a non-predictable name created in an atomic way in a dependable base directory is a solid way to go.
On Thu, Aug 14, 2025, 11:45 bugsbugsbux @.***> wrote:
bugsbugsbux left a comment (koalaman/shellcheck#3135) https://github.com/koalaman/shellcheck/issues/3135#issuecomment-3189515540
When I filed this issue I thought SC2103 was a hint to avoid a bad pattern, which I would have liked to know about before writing lots of pushd /; do-sth; popd and only came across when I used cd /; do-sth; cd - instead in some other script.
the cd in a shell script can cause side effects outside the script. So you always need to cd back to avoid this.
I don't think so: If you put cd / or pushd / in a script and execute it with bash myscript.sh or ./myscript.sh you end up where you started, on the other hand if you source any of the two scripts you end up in /.
Both, popd and cd - can fail or produce unexpected outcomes: cd - always fails before the first directory change (but not afterwards because it just switches back and forth between the current and previous folders) "-bash: cd: OLDPWD not set", popd always fails if there is no previous entry in the directory stack "-bash: popd: directory stack empty". Both commands should be conditional on the success of the corresponding previous directory change; or better avoided alltogether as SC2103 suggests.
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