The exec() family of functions replaces the current process image with a new process image, retaining the pid and pipes of the old process.

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3k views

How to “correctly” start an application from a shell

I find it hard to phrase the question precisely but I will give my best. I use dwm as my default window manager and dmenu as my application launcher. I hardly use GUI applications aside from my ...
23
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3answers
742 views

What does 'exec {fd}</dev/watchdog' do in Bash

That is literal, {fd} isnt a placeholder. I have a script that does this, and does not source in anything, nor does it reference {fd} anywhere else. Is this valid bash? exec {fd}</dev/watchdog
8
votes
2answers
351 views

reason for exec in wrapper scripts

I have seen wrapper script examples which in a nuthell are following: #!/bin/bash myprog=sleep echo "This is the wrapper script, it will exec "$myprog"" exec "$myprog" "$@" As seen above, they ...
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vote
1answer
98 views

How to understand the output of tracing running an external command in bash?

In Ubuntu, I run date directly in an interactive bash shell whose pid is 6913. $ date Wed Mar 2 23:57:44 EST 2016 At the same time, I trace the bash shell 6913 from another interactive bash shell ...
6
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4answers
336 views

Use case / practical example for Bash' builtin exec

Consider this from the documentation of Bash' builtin exec: exec replaces the shell without creating a new process Please provide a use case / practical example. I don’t understand how this ...
1
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0answers
70 views

How to understand the output of tracing running an external command in background via strace

In Ubuntu, I run date & in an interactive bash shell whose pid is 6913, and at the same time, trace the bash shell from another interactive bash shell by strace. The output of tracing the first ...
22
votes
4answers
1k views

What exactly happens when I execute a file in my shell?

So, I thought I had a good understanding of this, but just ran a test (in response to a conversation where I disagreed with someone) and found that my understanding is flawed... In as much detail as ...
11
votes
4answers
5k views

How do fork and exec work?

I don't have much experience, just trying to get involved into the processes how do they interpret to hardware from user level. So when a command is fired from a shell, fork() inherits a child ...
5
votes
2answers
13k views

Using exec and tee to redirect logs to stdout and a log file in the same time [duplicate]

In a bash script, how can I redirect all standard outputs to a log file and tee the output on the screen using exec ? log_file="$HOME/logs/install.txt-`date +'%Y-%m-%d_%H-%M-%S'`" [ -f "$log_file" ] |...
5
votes
3answers
7k views

Copy stdout and stderr to a log file and leave them on the console within the script itself

Using bash, how do I copy stderr and stdout to a log file and also leave them displayed on the console? I would like to do this within the script itself using an exec. I tried with exec &>&...
1
vote
1answer
133 views

fork() and exec() confusion

As when we do fork on current process, our process as parent process generates child process with same characteristics but different process IDs. So after that, when we do exec() in our child process, ...
0
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3answers
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Is reparenting from the shell possible?

This question is closely related to How to "correctly" start an application from a shell but tries to tackle a more specific problem. How can I spawn an application from a shell and thereby ...
5
votes
2answers
367 views

Is it possible to exec some commands in a subshell without immediately exiting afterwards?

I use the fish shell and would like to be able to "source" some shell scripts written with sh-compatible syntax, which fish cannot read. For example lots of software expects you to source some shell ...
3
votes
1answer
64 views

What kinds of commands can run with exec?

What kinds of commands can run with exec? For example, executable files, builtin commands, shell script, compound commands (e.g. looping, conditional branching), pipeline, command list, commands ...
2
votes
1answer
166 views

find with -exec eval of $0 [duplicate]

In the following command I would like to know why $0 was evaluated to the file found by find and not the echo command. $ find . -type f -perm -u=x -exec bash -c ' /bin/echo $0 is the name of the ...
0
votes
3answers
474 views

Bash in php exec in webpage don't colors for png and mp3 files on Linux

I have code like this in php: header("Content-Type: text/plain"); exec("/bin/bash -c 'ls --color=always'", $result); echo implode("\n", $result); and I've got result (escape is not visible) ...
0
votes
1answer
370 views

Cp with full renamed path in execl c program

I need to copy file and rename it in execl function so i did: if ( fileExists(new_dest) ){ /*function in which i rename the file by gtk dialog*/ renameDialog(fileName); printf("%s\n",...