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| # Bash | |
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| The above works in virtually all versions of Bash. Bash version 3 also allows regular expressions: | The above works in virtually all versions of Bash. Bash version 3 (and up) also allows regular expressions: |
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| if [[ $foo =~ ab*c ]] # bash 3, matches abbbbcde, or ac, etc. | # Bash my_re='ab*c' if [[ $foo =~ $my_re ]] # bash 3, matches abbbbcde, or ac, etc. |
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For more hints on string manipulations in Bash, see [[BashFAQ/100|FAQ #100]]. |
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| # Bourne | |
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| if echo "$foo" | grep bar >/dev/null; then ... | # Bourne if echo "$foo" | grep bar >/dev/null 2>&1; then ... |
How do I determine whether a variable contains a substring?
In BASH:
# Bash if [[ $foo = *bar* ]]
The above works in virtually all versions of Bash. Bash version 3 (and up) also allows regular expressions:
# Bash my_re='ab*c' if [[ $foo =~ $my_re ]] # bash 3, matches abbbbcde, or ac, etc.
For more hints on string manipulations in Bash, see FAQ #100.
If you are programming in the BourneShell instead of Bash, there is a more portable (but less pretty) syntax:
# Bourne
case "$foo" in
*bar*) .... ;;
esaccase allows you to match variables against globbing-style patterns (including extended globs, if your shell offers them). If you need a portable way to match variables against regular expressions, use grep or egrep.
# Bourne if echo "$foo" | grep bar >/dev/null 2>&1; then ...