A contrived example... given FOO="/foo/bar/baz" this works (in bash) BAR=$(basename $FOO) # result is BAR="baz" BAZ=${BAR:0:1} # result is BAZ="b" this doesn't BAZ=${$(basename $FOO):0:1} #...

Bumped into an unexpected bash/sh behavior and I wonder someone can explain the rationale behind it, and provide a solution to the question below. In an interactive bash shell session, I execute: ...

How can I pipe the stdout of multiple commands to a single command? Example 1: combine and sort the output of all three echo commands: echo zzz; echo aaa; echo kkk desired output: aaa kkk zzz...

Here is minimal code for issue demonstration: http://pastebin.com/5TXDpSh5 #!/bin/bash set -e set -o pipefail function echoTraps() { echo "= on start:" trap -p trap -- 'echo func-EXIT' EXIT e...

As far as I know there are two ways to create local variables in a bash function: create a subshell or declare every variable as local. For example: # using local function foo { local count for...

In a script.sh, source a.sh source b.sh CMD1 CMD2 CMD3 how can I replace the source *.sh with their content (without executing the commands)? I would like to see what the bash interpreter execu...

I try to send command via ssh which looks like this: ssh [email protected] "echo $(uname -a)" But my problem is, that $(uname -a) part actually create a subshell and executes not on 1...

So here is my problem, I have this script I wrote where I'm exporting two variables however they're not making it into the subshell. The point of this script is to change a users password and cle...

In the manpage for bash, under the "Compound Commands" section, there are the following two entries: (list) list is executed in a subshell environment (see COMMAND EXECUTION ENVIRONMENT below). ...

I've been trying to get a for loop to run a bunch of commands sort of simultaneously and was attempting to do it via subshells. Ive managed to cobble together the script below to test and it seems ...

When I execute git branch on the command line I get a list of all the branches on a repo, however when I execute $(git branch) in a sub-shell, it first prints out a list of files in the top level f...

I have a bash script start.sh which looks like this: for thing in foo bar; do { background_processor $thing cleanup_on_exit $thing } & done This does what I want: I run start.sh, it exit...

I'm wondering what's the difference between these two grammar in bash: ( &) and ( ) &. The only difference that I noticed is, (tty &) will return "not a tty" while (tty) & will ret...

Edit: My comment below regarding sed 's@^@ @' <(f1) is incorrect While $BASH_SUBSHELL indicates that we are in the same level as the launch, the variables are lost in the main script. based on ...

Yesterday it was suggested to me that using command substitution in bash causes an unnecessary subshell to be spawned. The advice was specific to this use case: # Extra subshell spawned foo=$(comm...

Given a file "foo.txt", created from: $ seq 1 10 > "foo.txt" I'm trying to read both the first and last line of the file, and I started by redirecting the file to a subshell, so that the list...

I have the following code: #!/bin/bash read -t1 < <(stat -t "/my/mountpoint") if [ $? -eq 1 ]; then echo NFS mount stale. Removing... umount -f -l /my/mountpoint fi How do I mute the o...

I want to use the magic of subshells and redirection with the python subprocess module, but it doesn't seem to work, complaining about unexpected tokens are the parenthesis. For example, the comman...

Let's say I have a bash function Yadda() { # time-consuming processes that must take place sequentially # the result will be appended >> $OUTFILE # $OUTFILE is set by the main body of the...