Questions tagged [for]

A tag to denote any questions relating to for loops

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3
votes
2answers
2k views

Why won't the for loop execute on directory

In the following script, the first for loop executes as expected, but not the second. I do not get any error, it seems that the script just hangs. HOME=/root/mydir DIR=$HOME/var DIRWORK=$HOME/Local ...
5
votes
5answers
24k views

Piping output to text file within a for loop

I'm trying to do the following within a for loop: Find files that satisfy a condition Echo the name of the files to a log file. Gzip the file. I can get the script to find the files and echo their ...
18
votes
4answers
7k views

${!FOO} and zsh

${!FOO} performs a double substitution in bash, meaning it takes the (string) value of FOO and uses it as a variable name. zsh doesn’t support this feature. Is there a way to make this work the same ...
2
votes
1answer
4k views

Why the behavior of while loop and for loop is different?

I am trying to read user and server details from file tempo.txt and then check the disk space usage of the file system on that unix account using another script server_disk_space.sh.But I am not able ...
20
votes
4answers
4k views

Avoiding errors due to unexpanded asterisk

In bash I often use for-loops such as the following for file in *.type; do sommecommand "$file"; done; to perform an operation for all files matching *.type. If no file with this ending is found ...
76
votes
4answers
75k views

In bash, is it possible to use an integer variable in a brace expansion

I have the following bash script: #!/bin/bash upperlim=10 for i in {0..10} do echo $i done for i in {0..$upperlim} do echo $i done The first for loop (without the variable upperlim in the loop ...
11
votes
2answers
26k views

for loop with multiline data

I need to create a script with a loop through a list of items. I want to insert a string in the script. I tried: for i in " a b c"; do echo "test "$i done But that only outputs one string: test a ...
0
votes
3answers
132 views

Why the code in a for loop is executed only in the first directory in a bash shell?

Under a directory called a there are many subfolders where I want to do something. The same for all. I do the following but it applies only to the first subdirectory: for i in "a/*" do ...
28
votes
3answers
83k views

In a bash shell script, writing a for loop that iterates over string values

In bash, I know that it is possible to write a for loop in which some loop control variable i iterates over specified integers. For example, I can write a bash shell script that prints the integers ...
12
votes
3answers
22k views

Multivariable For Loops

Is there a way to specify multiple variables (not just integers) in for loops in bash? I may have 2 files containing arbitrary text that i would need to work with. What i functionally need is ...
1
vote
1answer
176 views

What's the right way to reuse this one-liner?

I recently came up with the following one-liner: for f in *.mp3; do sha1sum $f | sed -r 's/[a-z]//g' | cut -c1-2 | awk '{ print ($1 >= 255) ? $1 - $1 + (1/3)*$1 : $1 }' | xargs -i id3v2 -T {} $f; ...
0
votes
2answers
5k views

Why does this incrementing for loop return a bad variable?

I'm trying to call this shell script from within the CLI of GRASS GIS: for (( day=5; day<367; day+5 )); do # commands that I've tested without a loop. done exit 0 returns Syntax error: Bad for ...

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